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This is gdb.info, produced by makeinfo version 6.5 from gdb.texinfo.
Copyright (C) 1988-2020 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual. Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."
INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Gdb: (gdb). The GNU debugger.
* gdbserver: (gdb) Server. The GNU debugging server.
END-INFO-DIR-ENTRY
This file documents the GNU debugger GDB.
This is the Tenth Edition, of 'Debugging with GDB: the GNU
Source-Level Debugger' for GDB (GDB) Version 9.2.
Copyright (C) 1988-2020 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
this GNU Manual. Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom."

File: gdb.info, Node: GDB/MI Tracepoint Commands, Next: GDB/MI Symbol Query, Prev: GDB/MI Data Manipulation, Up: GDB/MI
27.17 GDB/MI Tracepoint Commands
================================
The commands defined in this section implement MI support for
tracepoints. For detailed introduction, see *note Tracepoints::.
The '-trace-find' Command
-------------------------
Synopsis
........
-trace-find MODE [PARAMETERS...]
Find a trace frame using criteria defined by MODE and PARAMETERS.
The following table lists permissible modes and their parameters. For
details of operation, see *note tfind::.
'none'
No parameters are required. Stops examining trace frames.
'frame-number'
An integer is required as parameter. Selects tracepoint frame with
that index.
'tracepoint-number'
An integer is required as parameter. Finds next trace frame that
corresponds to tracepoint with the specified number.
'pc'
An address is required as parameter. Finds next trace frame that
corresponds to any tracepoint at the specified address.
'pc-inside-range'
Two addresses are required as parameters. Finds next trace frame
that corresponds to a tracepoint at an address inside the specified
range. Both bounds are considered to be inside the range.
'pc-outside-range'
Two addresses are required as parameters. Finds next trace frame
that corresponds to a tracepoint at an address outside the
specified range. Both bounds are considered to be inside the
range.
'line'
Line specification is required as parameter. *Note Specify
Location::. Finds next trace frame that corresponds to a
tracepoint at the specified location.
If 'none' was passed as MODE, the response does not have fields.
Otherwise, the response may have the following fields:
'found'
This field has either '0' or '1' as the value, depending on whether
a matching tracepoint was found.
'traceframe'
The index of the found traceframe. This field is present iff the
'found' field has value of '1'.
'tracepoint'
The index of the found tracepoint. This field is present iff the
'found' field has value of '1'.
'frame'
The information about the frame corresponding to the found trace
frame. This field is present only if a trace frame was found.
*Note GDB/MI Frame Information::, for description of this field.
GDB Command
...........
The corresponding GDB command is 'tfind'.
-trace-define-variable
----------------------
Synopsis
........
-trace-define-variable NAME [ VALUE ]
Create trace variable NAME if it does not exist. If VALUE is
specified, sets the initial value of the specified trace variable to
that value. Note that the NAME should start with the '$' character.
GDB Command
...........
The corresponding GDB command is 'tvariable'.
The '-trace-frame-collected' Command
------------------------------------
Synopsis
........
-trace-frame-collected
[--var-print-values VAR_PVAL]
[--comp-print-values COMP_PVAL]
[--registers-format REGFORMAT]
[--memory-contents]
This command returns the set of collected objects, register names,
trace state variable names, memory ranges and computed expressions that
have been collected at a particular trace frame. The optional
parameters to the command affect the output format in different ways.
See the output description table below for more details.
The reported names can be used in the normal manner to create varobjs
and inspect the objects themselves. The items returned by this command
are categorized so that it is clear which is a variable, which is a
register, which is a trace state variable, which is a memory range and
which is a computed expression.
For instance, if the actions were
collect myVar, myArray[myIndex], myObj.field, myPtr->field, myCount + 2
collect *(int*)0xaf02bef0@40
the object collected in its entirety would be 'myVar'. The object
'myArray' would be partially collected, because only the element at
index 'myIndex' would be collected. The remaining objects would be
computed expressions.
An example output would be:
(gdb)
-trace-frame-collected
^done,
explicit-variables=[{name="myVar",value="1"}],
computed-expressions=[{name="myArray[myIndex]",value="0"},
{name="myObj.field",value="0"},
{name="myPtr->field",value="1"},
{name="myCount + 2",value="3"},
{name="$tvar1 + 1",value="43970027"}],
registers=[{number="0",value="0x7fe2c6e79ec8"},
{number="1",value="0x0"},
{number="2",value="0x4"},
...
{number="125",value="0x0"}],
tvars=[{name="$tvar1",current="43970026"}],
memory=[{address="0x0000000000602264",length="4"},
{address="0x0000000000615bc0",length="4"}]
(gdb)
Where:
'explicit-variables'
The set of objects that have been collected in their entirety (as
opposed to collecting just a few elements of an array or a few
struct members). For each object, its name and value are printed.
The '--var-print-values' option affects how or whether the value
field is output. If VAR_PVAL is 0, then print only the names; if
it is 1, print also their values; and if it is 2, print the name,
type and value for simple data types, and the name and type for
arrays, structures and unions.
'computed-expressions'
The set of computed expressions that have been collected at the
current trace frame. The '--comp-print-values' option affects this
set like the '--var-print-values' option affects the
'explicit-variables' set. See above.
'registers'
The registers that have been collected at the current trace frame.
For each register collected, the name and current value are
returned. The value is formatted according to the
'--registers-format' option. See the '-data-list-register-values'
command for a list of the allowed formats. The default is 'x'.
'tvars'
The trace state variables that have been collected at the current
trace frame. For each trace state variable collected, the name and
current value are returned.
'memory'
The set of memory ranges that have been collected at the current
trace frame. Its content is a list of tuples. Each tuple
represents a collected memory range and has the following fields:
'address'
The start address of the memory range, as hexadecimal literal.
'length'
The length of the memory range, as decimal literal.
'contents'
The contents of the memory block, in hex. This field is only
present if the '--memory-contents' option is specified.
GDB Command
...........
There is no corresponding GDB command.
Example
.......
-trace-list-variables
---------------------
Synopsis
........
-trace-list-variables
Return a table of all defined trace variables. Each element of the
table has the following fields:
'name'
The name of the trace variable. This field is always present.
'initial'
The initial value. This is a 64-bit signed integer. This field is
always present.
'current'
The value the trace variable has at the moment. This is a 64-bit
signed integer. This field is absent iff current value is not
defined, for example if the trace was never run, or is presently
running.
GDB Command
...........
The corresponding GDB command is 'tvariables'.
Example
.......
(gdb)
-trace-list-variables
^done,trace-variables={nr_rows="1",nr_cols="3",
hdr=[{width="15",alignment="-1",col_name="name",colhdr="Name"},
{width="11",alignment="-1",col_name="initial",colhdr="Initial"},
{width="11",alignment="-1",col_name="current",colhdr="Current"}],
body=[variable={name="$trace_timestamp",initial="0"}
variable={name="$foo",initial="10",current="15"}]}
(gdb)
-trace-save
-----------
Synopsis
........
-trace-save [ -r ] [ -ctf ] FILENAME
Saves the collected trace data to FILENAME. Without the '-r' option,
the data is downloaded from the target and saved in a local file. With
the '-r' option the target is asked to perform the save.
By default, this command will save the trace in the tfile format.
You can supply the optional '-ctf' argument to save it the CTF format.
See *note Trace Files:: for more information about CTF.
GDB Command
...........
The corresponding GDB command is 'tsave'.
-trace-start
------------
Synopsis
........
-trace-start
Starts a tracing experiment. The result of this command does not
have any fields.
GDB Command
...........
The corresponding GDB command is 'tstart'.
-trace-status
-------------
Synopsis
........
-trace-status
Obtains the status of a tracing experiment. The result may include
the following fields:
'supported'
May have a value of either '0', when no tracing operations are
supported, '1', when all tracing operations are supported, or
'file' when examining trace file. In the latter case, examining of
trace frame is possible but new tracing experiement cannot be
started. This field is always present.
'running'
May have a value of either '0' or '1' depending on whether tracing
experiement is in progress on target. This field is present if
'supported' field is not '0'.
'stop-reason'
Report the reason why the tracing was stopped last time. This
field may be absent iff tracing was never stopped on target yet.
The value of 'request' means the tracing was stopped as result of
the '-trace-stop' command. The value of 'overflow' means the
tracing buffer is full. The value of 'disconnection' means tracing
was automatically stopped when GDB has disconnected. The value of
'passcount' means tracing was stopped when a tracepoint was passed
a maximal number of times for that tracepoint. This field is
present if 'supported' field is not '0'.
'stopping-tracepoint'
The number of tracepoint whose passcount as exceeded. This field
is present iff the 'stop-reason' field has the value of
'passcount'.
'frames'
'frames-created'
The 'frames' field is a count of the total number of trace frames
in the trace buffer, while 'frames-created' is the total created
during the run, including ones that were discarded, such as when a
circular trace buffer filled up. Both fields are optional.
'buffer-size'
'buffer-free'
These fields tell the current size of the tracing buffer and the
remaining space. These fields are optional.
'circular'
The value of the circular trace buffer flag. '1' means that the
trace buffer is circular and old trace frames will be discarded if
necessary to make room, '0' means that the trace buffer is linear
and may fill up.
'disconnected'
The value of the disconnected tracing flag. '1' means that tracing
will continue after GDB disconnects, '0' means that the trace run
will stop.
'trace-file'
The filename of the trace file being examined. This field is
optional, and only present when examining a trace file.
GDB Command
...........
The corresponding GDB command is 'tstatus'.
-trace-stop
-----------
Synopsis
........
-trace-stop
Stops a tracing experiment. The result of this command has the same
fields as '-trace-status', except that the 'supported' and 'running'
fields are not output.
GDB Command
...........
The corresponding GDB command is 'tstop'.

File: gdb.info, Node: GDB/MI Symbol Query, Next: GDB/MI File Commands, Prev: GDB/MI Tracepoint Commands, Up: GDB/MI
27.18 GDB/MI Symbol Query Commands
==================================
The '-symbol-info-functions' Command
------------------------------------
Synopsis
........
-symbol-info-functions [--include-nondebug]
[--type TYPE_REGEXP]
[--name NAME_REGEXP]
[--max-results LIMIT]
Return a list containing the names and types for all global functions
taken from the debug information. The functions are grouped by source
file, and shown with the line number on which each function is defined.
The '--include-nondebug' option causes the output to include code
symbols from the symbol table.
The options '--type' and '--name' allow the symbols returned to be
filtered based on either the name of the function, or the type signature
of the function.
The option '--max-results' restricts the command to return no more
than LIMIT results. If exactly LIMIT results are returned then there
might be additional results available if a higher limit is used.
GDB Command
...........
The corresponding GDB command is 'info functions'.
Example
.......
(gdb)
-symbol-info-functions
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="36", name="f4", type="void (int *)",
description="void f4(int *);"},
{line="42", name="main", type="int ()",
description="int main();"},
{line="30", name="f1", type="my_int_t (int, int)",
description="static my_int_t f1(int, int);"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="33", name="f2", type="float (another_float_t)",
description="float f2(another_float_t);"},
{line="39", name="f3", type="int (another_int_t)",
description="int f3(another_int_t);"},
{line="27", name="f1", type="another_float_t (int)",
description="static another_float_t f1(int);"}]}]}
(gdb)
-symbol-info-functions --name f1
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="30", name="f1", type="my_int_t (int, int)",
description="static my_int_t f1(int, int);"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="27", name="f1", type="another_float_t (int)",
description="static another_float_t f1(int);"}]}]}
(gdb)
-symbol-info-functions --type void
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="36", name="f4", type="void (int *)",
description="void f4(int *);"}]}]}
(gdb)
-symbol-info-functions --include-nondebug
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="36", name="f4", type="void (int *)",
description="void f4(int *);"},
{line="42", name="main", type="int ()",
description="int main();"},
{line="30", name="f1", type="my_int_t (int, int)",
description="static my_int_t f1(int, int);"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="33", name="f2", type="float (another_float_t)",
description="float f2(another_float_t);"},
{line="39", name="f3", type="int (another_int_t)",
description="int f3(another_int_t);"},
{line="27", name="f1", type="another_float_t (int)",
description="static another_float_t f1(int);"}]}],
nondebug=
[{address="0x0000000000400398",name="_init"},
{address="0x00000000004003b0",name="_start"},
...
]}
The '-symbol-info-module-functions' Command
-------------------------------------------
Synopsis
........
-symbol-info-module-functions [--module MODULE_REGEXP]
[--name NAME_REGEXP]
[--type TYPE_REGEXP]
Return a list containing the names of all known functions within all
know Fortran modules. The functions are grouped by source file and
containing module, and shown with the line number on which each function
is defined.
The option '--module' only returns results for modules matching
MODULE_REGEXP. The option '--name' only returns functions whose name
matches NAME_REGEXP, and '--type' only returns functions whose type
matches TYPE_REGEXP.
GDB Command
...........
The corresponding GDB command is 'info module functions'.
Example
.......
(gdb)
-symbol-info-module-functions
^done,symbols=
[{module="mod1",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
symbols=[{line="21",name="mod1::check_all",type="void (void)",
description="void mod1::check_all(void);"}]}]},
{module="mod2",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
symbols=[{line="30",name="mod2::check_var_i",type="void (void)",
description="void mod2::check_var_i(void);"}]}]},
{module="mod3",
files=[{filename="/projec/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/projec/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="21",name="mod3::check_all",type="void (void)",
description="void mod3::check_all(void);"},
{line="27",name="mod3::check_mod2",type="void (void)",
description="void mod3::check_mod2(void);"}]}]},
{module="modmany",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="35",name="modmany::check_some",type="void (void)",
description="void modmany::check_some(void);"}]}]},
{module="moduse",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="44",name="moduse::check_all",type="void (void)",
description="void moduse::check_all(void);"},
{line="49",name="moduse::check_var_x",type="void (void)",
description="void moduse::check_var_x(void);"}]}]}]
The '-symbol-info-module-variables' Command
-------------------------------------------
Synopsis
........
-symbol-info-module-variables [--module MODULE_REGEXP]
[--name NAME_REGEXP]
[--type TYPE_REGEXP]
Return a list containing the names of all known variables within all
know Fortran modules. The variables are grouped by source file and
containing module, and shown with the line number on which each variable
is defined.
The option '--module' only returns results for modules matching
MODULE_REGEXP. The option '--name' only returns variables whose name
matches NAME_REGEXP, and '--type' only returns variables whose type
matches TYPE_REGEXP.
GDB Command
...........
The corresponding GDB command is 'info module variables'.
Example
.......
(gdb)
-symbol-info-module-variables
^done,symbols=
[{module="mod1",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
symbols=[{line="18",name="mod1::var_const",type="integer(kind=4)",
description="integer(kind=4) mod1::var_const;"},
{line="17",name="mod1::var_i",type="integer(kind=4)",
description="integer(kind=4) mod1::var_i;"}]}]},
{module="mod2",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
symbols=[{line="28",name="mod2::var_i",type="integer(kind=4)",
description="integer(kind=4) mod2::var_i;"}]}]},
{module="mod3",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="18",name="mod3::mod1",type="integer(kind=4)",
description="integer(kind=4) mod3::mod1;"},
{line="17",name="mod3::mod2",type="integer(kind=4)",
description="integer(kind=4) mod3::mod2;"},
{line="19",name="mod3::var_i",type="integer(kind=4)",
description="integer(kind=4) mod3::var_i;"}]}]},
{module="modmany",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="33",name="modmany::var_a",type="integer(kind=4)",
description="integer(kind=4) modmany::var_a;"},
{line="33",name="modmany::var_b",type="integer(kind=4)",
description="integer(kind=4) modmany::var_b;"},
{line="33",name="modmany::var_c",type="integer(kind=4)",
description="integer(kind=4) modmany::var_c;"},
{line="33",name="modmany::var_i",type="integer(kind=4)",
description="integer(kind=4) modmany::var_i;"}]}]},
{module="moduse",
files=[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="42",name="moduse::var_x",type="integer(kind=4)",
description="integer(kind=4) moduse::var_x;"},
{line="42",name="moduse::var_y",type="integer(kind=4)",
description="integer(kind=4) moduse::var_y;"}]}]}]
The '-symbol-info-modules' Command
----------------------------------
Synopsis
........
-symbol-info-modules [--name NAME_REGEXP]
[--max-results LIMIT]
Return a list containing the names of all known Fortran modules. The
modules are grouped by source file, and shown with the line number on
which each modules is defined.
The option '--name' allows the modules returned to be filtered based
the name of the module.
The option '--max-results' restricts the command to return no more
than LIMIT results. If exactly LIMIT results are returned then there
might be additional results available if a higher limit is used.
GDB Command
...........
The corresponding GDB command is 'info modules'.
Example
.......
(gdb)
-symbol-info-modules
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
symbols=[{line="16",name="mod1"},
{line="22",name="mod2"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="16",name="mod3"},
{line="22",name="modmany"},
{line="26",name="moduse"}]}]}
(gdb)
-symbol-info-modules --name mod[123]
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules-2.f90",
symbols=[{line="16",name="mod1"},
{line="22",name="mod2"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
fullname="/project/gdb/testsuite/gdb.mi/mi-fortran-modules.f90",
symbols=[{line="16",name="mod3"}]}]}
The '-symbol-info-types' Command
--------------------------------
Synopsis
........
-symbol-info-types [--name NAME_REGEXP]
[--max-results LIMIT]
Return a list of all defined types. The types are grouped by source
file, and shown with the line number on which each user defined type is
defined. Some base types are not defined in the source code but are
added to the debug information by the compiler, for example 'int',
'float', etc.; these types do not have an associated line number.
The option '--name' allows the list of types returned to be filtered
by name.
The option '--max-results' restricts the command to return no more
than LIMIT results. If exactly LIMIT results are returned then there
might be additional results available if a higher limit is used.
GDB Command
...........
The corresponding GDB command is 'info types'.
Example
.......
(gdb)
-symbol-info-types
^done,symbols=
{debug=
[{filename="gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{name="float"},
{name="int"},
{line="27",name="typedef int my_int_t;"}]},
{filename="gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb.mi/mi-sym-info-2.c",
symbols=[{line="24",name="typedef float another_float_t;"},
{line="23",name="typedef int another_int_t;"},
{name="float"},
{name="int"}]}]}
(gdb)
-symbol-info-types --name _int_
^done,symbols=
{debug=
[{filename="gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="27",name="typedef int my_int_t;"}]},
{filename="gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb.mi/mi-sym-info-2.c",
symbols=[{line="23",name="typedef int another_int_t;"}]}]}
The '-symbol-info-variables' Command
------------------------------------
Synopsis
........
-symbol-info-variables [--include-nondebug]
[--type TYPE_REGEXP]
[--name NAME_REGEXP]
[--max-results LIMIT]
Return a list containing the names and types for all global variables
taken from the debug information. The variables are grouped by source
file, and shown with the line number on which each variable is defined.
The '--include-nondebug' option causes the output to include data
symbols from the symbol table.
The options '--type' and '--name' allow the symbols returned to be
filtered based on either the name of the variable, or the type of the
variable.
The option '--max-results' restricts the command to return no more
than LIMIT results. If exactly LIMIT results are returned then there
might be additional results available if a higher limit is used.
GDB Command
...........
The corresponding GDB command is 'info variables'.
Example
.......
(gdb)
-symbol-info-variables
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="25",name="global_f1",type="float",
description="static float global_f1;"},
{line="24",name="global_i1",type="int",
description="static int global_i1;"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="21",name="global_f2",type="int",
description="int global_f2;"},
{line="20",name="global_i2",type="int",
description="int global_i2;"},
{line="19",name="global_f1",type="float",
description="static float global_f1;"},
{line="18",name="global_i1",type="int",
description="static int global_i1;"}]}]}
(gdb)
-symbol-info-variables --name f1
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="25",name="global_f1",type="float",
description="static float global_f1;"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="19",name="global_f1",type="float",
description="static float global_f1;"}]}]}
(gdb)
-symbol-info-variables --type float
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="25",name="global_f1",type="float",
description="static float global_f1;"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="19",name="global_f1",type="float",
description="static float global_f1;"}]}]}
(gdb)
-symbol-info-variables --include-nondebug
^done,symbols=
{debug=
[{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-1.c",
symbols=[{line="25",name="global_f1",type="float",
description="static float global_f1;"},
{line="24",name="global_i1",type="int",
description="static int global_i1;"}]},
{filename="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
fullname="/project/gdb/testsuite/gdb.mi/mi-sym-info-2.c",
symbols=[{line="21",name="global_f2",type="int",
description="int global_f2;"},
{line="20",name="global_i2",type="int",
description="int global_i2;"},
{line="19",name="global_f1",type="float",
description="static float global_f1;"},
{line="18",name="global_i1",type="int",
description="static int global_i1;"}]}],
nondebug=
[{address="0x00000000004005d0",name="_IO_stdin_used"},
{address="0x00000000004005d8",name="__dso_handle"}
...
]}
The '-symbol-list-lines' Command
--------------------------------
Synopsis
........
-symbol-list-lines FILENAME
Print the list of lines that contain code and their associated
program addresses for the given source filename. The entries are sorted
in ascending PC order.
GDB Command
...........
There is no corresponding GDB command.
Example
.......
(gdb)
-symbol-list-lines basics.c
^done,lines=[{pc="0x08048554",line="7"},{pc="0x0804855a",line="8"}]
(gdb)

File: gdb.info, Node: GDB/MI File Commands, Next: GDB/MI Target Manipulation, Prev: GDB/MI Symbol Query, Up: GDB/MI
27.19 GDB/MI File Commands
==========================
This section describes the GDB/MI commands to specify executable file
names and to read in and obtain symbol table information.
The '-file-exec-and-symbols' Command
------------------------------------
Synopsis
........
-file-exec-and-symbols FILE
Specify the executable file to be debugged. This file is the one
from which the symbol table is also read. If no file is specified, the
command clears the executable and symbol information. If breakpoints
are set when using this command with no arguments, GDB will produce
error messages. Otherwise, no output is produced, except a completion
notification.
GDB Command
...........
The corresponding GDB command is 'file'.
Example
.......
(gdb)
-file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
The '-file-exec-file' Command
-----------------------------
Synopsis
........
-file-exec-file FILE
Specify the executable file to be debugged. Unlike
'-file-exec-and-symbols', the symbol table is _not_ read from this file.
If used without argument, GDB clears the information about the
executable file. No output is produced, except a completion
notification.
GDB Command
...........
The corresponding GDB command is 'exec-file'.
Example
.......
(gdb)
-file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
The '-file-list-exec-source-file' Command
-----------------------------------------
Synopsis
........
-file-list-exec-source-file
List the line number, the current source file, and the absolute path
to the current source file for the current executable. The macro
information field has a value of '1' or '0' depending on whether or not
the file includes preprocessor macro information.
GDB Command
...........
The GDB equivalent is 'info source'
Example
.......
(gdb)
123-file-list-exec-source-file
123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1"
(gdb)
The '-file-list-exec-source-files' Command
------------------------------------------
Synopsis
........
-file-list-exec-source-files
List the source files for the current executable.
It will always output both the filename and fullname (absolute file
name) of a source file.
GDB Command
...........
The GDB equivalent is 'info sources'. 'gdbtk' has an analogous command
'gdb_listfiles'.
Example
.......
(gdb)
-file-list-exec-source-files
^done,files=[
{file=foo.c,fullname=/home/foo.c},
{file=/home/bar.c,fullname=/home/bar.c},
{file=gdb_could_not_find_fullpath.c}]
(gdb)
The '-file-list-shared-libraries' Command
-----------------------------------------
Synopsis
........
-file-list-shared-libraries [ REGEXP ]
List the shared libraries in the program. With a regular expression
REGEXP, only those libraries whose names match REGEXP are listed.
GDB Command
...........
The corresponding GDB command is 'info shared'. The fields have a
similar meaning to the '=library-loaded' notification. The 'ranges'
field specifies the multiple segments belonging to this library. Each
range has the following fields:
'from'
The address defining the inclusive lower bound of the segment.
'to'
The address defining the exclusive upper bound of the segment.
Example
.......
(gdb)
-file-list-exec-source-files
^done,shared-libraries=[
{id="/lib/libfoo.so",target-name="/lib/libfoo.so",host-name="/lib/libfoo.so",symbols-loaded="1",thread-group="i1",ranges=[{from="0x72815989",to="0x728162c0"}]},
{id="/lib/libbar.so",target-name="/lib/libbar.so",host-name="/lib/libbar.so",symbols-loaded="1",thread-group="i1",ranges=[{from="0x76ee48c0",to="0x76ee9160"}]}]
(gdb)
The '-file-symbol-file' Command
-------------------------------
Synopsis
........
-file-symbol-file FILE
Read symbol table info from the specified FILE argument. When used
without arguments, clears GDB's symbol table info. No output is
produced, except for a completion notification.
GDB Command
...........
The corresponding GDB command is 'symbol-file'.
Example
.......
(gdb)
-file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)

File: gdb.info, Node: GDB/MI Target Manipulation, Next: GDB/MI File Transfer Commands, Prev: GDB/MI File Commands, Up: GDB/MI
27.20 GDB/MI Target Manipulation Commands
=========================================
The '-target-attach' Command
----------------------------
Synopsis
........
-target-attach PID | GID | FILE
Attach to a process PID or a file FILE outside of GDB, or a thread
group GID. If attaching to a thread group, the id previously returned
by '-list-thread-groups --available' must be used.
GDB Command
...........
The corresponding GDB command is 'attach'.
Example
.......
(gdb)
-target-attach 34
=thread-created,id="1"
*stopped,thread-id="1",frame={addr="0xb7f7e410",func="bar",args=[]}
^done
(gdb)
The '-target-detach' Command
----------------------------
Synopsis
........
-target-detach [ PID | GID ]
Detach from the remote target which normally resumes its execution.
If either PID or GID is specified, detaches from either the specified
process, or specified thread group. There's no output.
GDB Command
...........
The corresponding GDB command is 'detach'.
Example
.......
(gdb)
-target-detach
^done
(gdb)
The '-target-disconnect' Command
--------------------------------
Synopsis
........
-target-disconnect
Disconnect from the remote target. There's no output and the target
is generally not resumed.
GDB Command
...........
The corresponding GDB command is 'disconnect'.
Example
.......
(gdb)
-target-disconnect
^done
(gdb)
The '-target-download' Command
------------------------------
Synopsis
........
-target-download
Loads the executable onto the remote target. It prints out an update
message every half second, which includes the fields:
'section'
The name of the section.
'section-sent'
The size of what has been sent so far for that section.
'section-size'
The size of the section.
'total-sent'
The total size of what was sent so far (the current and the
previous sections).
'total-size'
The size of the overall executable to download.
Each message is sent as status record (*note GDB/MI Output Syntax:
GDB/MI Output Syntax.).
In addition, it prints the name and size of the sections, as they are
downloaded. These messages include the following fields:
'section'
The name of the section.
'section-size'
The size of the section.
'total-size'
The size of the overall executable to download.
At the end, a summary is printed.
GDB Command
...........
The corresponding GDB command is 'load'.
Example
.......
Note: each status message appears on a single line. Here the messages
have been broken down so that they can fit onto a page.
(gdb)
-target-download
+download,{section=".text",section-size="6668",total-size="9880"}
+download,{section=".text",section-sent="512",section-size="6668",
total-sent="512",total-size="9880"}
+download,{section=".text",section-sent="1024",section-size="6668",
total-sent="1024",total-size="9880"}
+download,{section=".text",section-sent="1536",section-size="6668",
total-sent="1536",total-size="9880"}
+download,{section=".text",section-sent="2048",section-size="6668",
total-sent="2048",total-size="9880"}
+download,{section=".text",section-sent="2560",section-size="6668",
total-sent="2560",total-size="9880"}
+download,{section=".text",section-sent="3072",section-size="6668",
total-sent="3072",total-size="9880"}
+download,{section=".text",section-sent="3584",section-size="6668",
total-sent="3584",total-size="9880"}
+download,{section=".text",section-sent="4096",section-size="6668",
total-sent="4096",total-size="9880"}
+download,{section=".text",section-sent="4608",section-size="6668",
total-sent="4608",total-size="9880"}
+download,{section=".text",section-sent="5120",section-size="6668",
total-sent="5120",total-size="9880"}
+download,{section=".text",section-sent="5632",section-size="6668",
total-sent="5632",total-size="9880"}
+download,{section=".text",section-sent="6144",section-size="6668",
total-sent="6144",total-size="9880"}
+download,{section=".text",section-sent="6656",section-size="6668",
total-sent="6656",total-size="9880"}
+download,{section=".init",section-size="28",total-size="9880"}
+download,{section=".fini",section-size="28",total-size="9880"}
+download,{section=".data",section-size="3156",total-size="9880"}
+download,{section=".data",section-sent="512",section-size="3156",
total-sent="7236",total-size="9880"}
+download,{section=".data",section-sent="1024",section-size="3156",
total-sent="7748",total-size="9880"}
+download,{section=".data",section-sent="1536",section-size="3156",
total-sent="8260",total-size="9880"}
+download,{section=".data",section-sent="2048",section-size="3156",
total-sent="8772",total-size="9880"}
+download,{section=".data",section-sent="2560",section-size="3156",
total-sent="9284",total-size="9880"}
+download,{section=".data",section-sent="3072",section-size="3156",
total-sent="9796",total-size="9880"}
^done,address="0x10004",load-size="9880",transfer-rate="6586",
write-rate="429"
(gdb)
GDB Command
...........
No equivalent.
Example
.......
N.A.
The '-target-flash-erase' Command
---------------------------------
Synopsis
........
-target-flash-erase
Erases all known flash memory regions on the target.
The corresponding GDB command is 'flash-erase'.
The output is a list of flash regions that have been erased, with
starting addresses and memory region sizes.
(gdb)
-target-flash-erase
^done,erased-regions={address="0x0",size="0x40000"}
(gdb)
The '-target-select' Command
----------------------------
Synopsis
........
-target-select TYPE PARAMETERS ...
Connect GDB to the remote target. This command takes two args:
'TYPE'
The type of target, for instance 'remote', etc.
'PARAMETERS'
Device names, host names and the like. *Note Commands for Managing
Targets: Target Commands, for more details.
The output is a connection notification, followed by the address at
which the target program is, in the following form:
^connected,addr="ADDRESS",func="FUNCTION NAME",
args=[ARG LIST]
GDB Command
...........
The corresponding GDB command is 'target'.
Example
.......
(gdb)
-target-select remote /dev/ttya
^connected,addr="0xfe00a300",func="??",args=[]
(gdb)

File: gdb.info, Node: GDB/MI File Transfer Commands, Next: GDB/MI Ada Exceptions Commands, Prev: GDB/MI Target Manipulation, Up: GDB/MI
27.21 GDB/MI File Transfer Commands
===================================
The '-target-file-put' Command
------------------------------
Synopsis
........
-target-file-put HOSTFILE TARGETFILE
Copy file HOSTFILE from the host system (the machine running GDB) to
TARGETFILE on the target system.
GDB Command
...........
The corresponding GDB command is 'remote put'.
Example
.......
(gdb)
-target-file-put localfile remotefile
^done
(gdb)
The '-target-file-get' Command
------------------------------
Synopsis
........
-target-file-get TARGETFILE HOSTFILE
Copy file TARGETFILE from the target system to HOSTFILE on the host
system.
GDB Command
...........
The corresponding GDB command is 'remote get'.
Example
.......
(gdb)
-target-file-get remotefile localfile
^done
(gdb)
The '-target-file-delete' Command
---------------------------------
Synopsis
........
-target-file-delete TARGETFILE
Delete TARGETFILE from the target system.
GDB Command
...........
The corresponding GDB command is 'remote delete'.
Example
.......
(gdb)
-target-file-delete remotefile
^done
(gdb)

File: gdb.info, Node: GDB/MI Ada Exceptions Commands, Next: GDB/MI Support Commands, Prev: GDB/MI File Transfer Commands, Up: GDB/MI
27.22 Ada Exceptions GDB/MI Commands
====================================
The '-info-ada-exceptions' Command
----------------------------------
Synopsis
........
-info-ada-exceptions [ REGEXP]
List all Ada exceptions defined within the program being debugged.
With a regular expression REGEXP, only those exceptions whose names
match REGEXP are listed.
GDB Command
...........
The corresponding GDB command is 'info exceptions'.
Result
......
The result is a table of Ada exceptions. The following columns are
defined for each exception:
'name'
The name of the exception.
'address'
The address of the exception.
Example
.......
-info-ada-exceptions aint
^done,ada-exceptions={nr_rows="2",nr_cols="2",
hdr=[{width="1",alignment="-1",col_name="name",colhdr="Name"},
{width="1",alignment="-1",col_name="address",colhdr="Address"}],
body=[{name="constraint_error",address="0x0000000000613da0"},
{name="const.aint_global_e",address="0x0000000000613b00"}]}
Catching Ada Exceptions
-----------------------
The commands describing how to ask GDB to stop when a program raises an
exception are described at *note Ada Exception GDB/MI Catchpoint
Commands::.

File: gdb.info, Node: GDB/MI Support Commands, Next: GDB/MI Miscellaneous Commands, Prev: GDB/MI Ada Exceptions Commands, Up: GDB/MI
27.23 GDB/MI Support Commands
=============================
Since new commands and features get regularly added to GDB/MI, some
commands are available to help front-ends query the debugger about
support for these capabilities. Similarly, it is also possible to query
GDB about target support of certain features.
The '-info-gdb-mi-command' Command
----------------------------------
Synopsis
........
-info-gdb-mi-command CMD_NAME
Query support for the GDB/MI command named CMD_NAME.
Note that the dash ('-') starting all GDB/MI commands is technically
not part of the command name (*note GDB/MI Input Syntax::), and thus
should be omitted in CMD_NAME. However, for ease of use, this command
also accepts the form with the leading dash.
GDB Command
...........
There is no corresponding GDB command.
Result
......
The result is a tuple. There is currently only one field:
'exists'
This field is equal to '"true"' if the GDB/MI command exists,
'"false"' otherwise.
Example
.......
Here is an example where the GDB/MI command does not exist:
-info-gdb-mi-command unsupported-command
^done,command={exists="false"}
And here is an example where the GDB/MI command is known to the
debugger:
-info-gdb-mi-command symbol-list-lines
^done,command={exists="true"}
The '-list-features' Command
----------------------------
Returns a list of particular features of the MI protocol that this
version of gdb implements. A feature can be a command, or a new field
in an output of some command, or even an important bugfix. While a
frontend can sometimes detect presence of a feature at runtime, it is
easier to perform detection at debugger startup.
The command returns a list of strings, with each string naming an
available feature. Each returned string is just a name, it does not
have any internal structure. The list of possible feature names is
given below.
Example output:
(gdb) -list-features
^done,result=["feature1","feature2"]
The current list of features is:
'frozen-varobjs'
Indicates support for the '-var-set-frozen' command, as well as
possible presence of the 'frozen' field in the output of
'-varobj-create'.
'pending-breakpoints'
Indicates support for the '-f' option to the '-break-insert'
command.
'python'
Indicates Python scripting support, Python-based pretty-printing
commands, and possible presence of the 'display_hint' field in the
output of '-var-list-children'
'thread-info'
Indicates support for the '-thread-info' command.
'data-read-memory-bytes'
Indicates support for the '-data-read-memory-bytes' and the
'-data-write-memory-bytes' commands.
'breakpoint-notifications'
Indicates that changes to breakpoints and breakpoints created via
the CLI will be announced via async records.
'ada-task-info'
Indicates support for the '-ada-task-info' command.
'language-option'
Indicates that all GDB/MI commands accept the '--language' option
(*note Context management::).
'info-gdb-mi-command'
Indicates support for the '-info-gdb-mi-command' command.
'undefined-command-error-code'
Indicates support for the "undefined-command" error code in error
result records, produced when trying to execute an undefined GDB/MI
command (*note GDB/MI Result Records::).
'exec-run-start-option'
Indicates that the '-exec-run' command supports the '--start'
option (*note GDB/MI Program Execution::).
'data-disassemble-a-option'
Indicates that the '-data-disassemble' command supports the '-a'
option (*note GDB/MI Data Manipulation::).
The '-list-target-features' Command
-----------------------------------
Returns a list of particular features that are supported by the target.
Those features affect the permitted MI commands, but unlike the features
reported by the '-list-features' command, the features depend on which
target GDB is using at the moment. Whenever a target can change, due to
commands such as '-target-select', '-target-attach' or '-exec-run', the
list of target features may change, and the frontend should obtain it
again. Example output:
(gdb) -list-target-features
^done,result=["async"]
The current list of features is:
'async'
Indicates that the target is capable of asynchronous command
execution, which means that GDB will accept further commands while
the target is running.
'reverse'
Indicates that the target is capable of reverse execution. *Note
Reverse Execution::, for more information.

File: gdb.info, Node: GDB/MI Miscellaneous Commands, Prev: GDB/MI Support Commands, Up: GDB/MI
27.24 Miscellaneous GDB/MI Commands
===================================
The '-gdb-exit' Command
-----------------------
Synopsis
........
-gdb-exit
Exit GDB immediately.
GDB Command
...........
Approximately corresponds to 'quit'.
Example
.......
(gdb)
-gdb-exit
^exit
The '-gdb-set' Command
----------------------
Synopsis
........
-gdb-set
Set an internal GDB variable.
GDB Command
...........
The corresponding GDB command is 'set'.
Example
.......
(gdb)
-gdb-set $foo=3
^done
(gdb)
The '-gdb-show' Command
-----------------------
Synopsis
........
-gdb-show
Show the current value of a GDB variable.
GDB Command
...........
The corresponding GDB command is 'show'.
Example
.......
(gdb)
-gdb-show annotate
^done,value="0"
(gdb)
The '-gdb-version' Command
--------------------------
Synopsis
........
-gdb-version
Show version information for GDB. Used mostly in testing.
GDB Command
...........
The GDB equivalent is 'show version'. GDB by default shows this
information when you start an interactive session.
Example
.......
(gdb)
-gdb-version
~GNU gdb 5.2.1
~Copyright 2000 Free Software Foundation, Inc.
~GDB is free software, covered by the GNU General Public License, and
~you are welcome to change it and/or distribute copies of it under
~ certain conditions.
~Type "show copying" to see the conditions.
~There is absolutely no warranty for GDB. Type "show warranty" for
~ details.
~This GDB was configured as
"--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
^done
(gdb)
The '-list-thread-groups' Command
---------------------------------
Synopsis
--------
-list-thread-groups [ --available ] [ --recurse 1 ] [ GROUP ... ]
Lists thread groups (*note Thread groups::). When a single thread
group is passed as the argument, lists the children of that group. When
several thread group are passed, lists information about those thread
groups. Without any parameters, lists information about all top-level
thread groups.
Normally, thread groups that are being debugged are reported. With
the '--available' option, GDB reports thread groups available on the
target.
The output of this command may have either a 'threads' result or a
'groups' result. The 'thread' result has a list of tuples as value,
with each tuple describing a thread (*note GDB/MI Thread Information::).
The 'groups' result has a list of tuples as value, each tuple describing
a thread group. If top-level groups are requested (that is, no
parameter is passed), or when several groups are passed, the output
always has a 'groups' result. The format of the 'group' result is
described below.
To reduce the number of roundtrips it's possible to list thread
groups together with their children, by passing the '--recurse' option
and the recursion depth. Presently, only recursion depth of 1 is
permitted. If this option is present, then every reported thread group
will also include its children, either as 'group' or 'threads' field.
In general, any combination of option and parameters is permitted,
with the following caveats:
* When a single thread group is passed, the output will typically be
the 'threads' result. Because threads may not contain anything,
the 'recurse' option will be ignored.
* When the '--available' option is passed, limited information may be
available. In particular, the list of threads of a process might
be inaccessible. Further, specifying specific thread groups might
not give any performance advantage over listing all thread groups.
The frontend should assume that '-list-thread-groups --available'
is always an expensive operation and cache the results.
The 'groups' result is a list of tuples, where each tuple may have
the following fields:
'id'
Identifier of the thread group. This field is always present. The
identifier is an opaque string; frontends should not try to convert
it to an integer, even though it might look like one.
'type'
The type of the thread group. At present, only 'process' is a
valid type.
'pid'
The target-specific process identifier. This field is only present
for thread groups of type 'process' and only if the process exists.
'exit-code'
The exit code of this group's last exited thread, formatted in
octal. This field is only present for thread groups of type
'process' and only if the process is not running.
'num_children'
The number of children this thread group has. This field may be
absent for an available thread group.
'threads'
This field has a list of tuples as value, each tuple describing a
thread. It may be present if the '--recurse' option is specified,
and it's actually possible to obtain the threads.
'cores'
This field is a list of integers, each identifying a core that one
thread of the group is running on. This field may be absent if
such information is not available.
'executable'
The name of the executable file that corresponds to this thread
group. The field is only present for thread groups of type
'process', and only if there is a corresponding executable file.
Example
-------
gdb
-list-thread-groups
^done,groups=[{id="17",type="process",pid="yyy",num_children="2"}]
-list-thread-groups 17
^done,threads=[{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]},state="running"},
{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
frame={level="0",addr="0x0804891f",func="foo",args=[{name="i",value="10"}],
file="/tmp/a.c",fullname="/tmp/a.c",line="158",arch="i386:x86_64"},state="running"}]]
-list-thread-groups --available
^done,groups=[{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]}]
-list-thread-groups --available --recurse 1
^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
{id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},..]
-list-thread-groups --available --recurse 1 17 18
^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]},
{id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},...]
The '-info-os' Command
----------------------
Synopsis
........
-info-os [ TYPE ]
If no argument is supplied, the command returns a table of available
operating-system-specific information types. If one of these types is
supplied as an argument TYPE, then the command returns a table of data
of that type.
The types of information available depend on the target operating
system.
GDB Command
...........
The corresponding GDB command is 'info os'.
Example
.......
When run on a GNU/Linux system, the output will look something like
this:
gdb
-info-os
^done,OSDataTable={nr_rows="10",nr_cols="3",
hdr=[{width="10",alignment="-1",col_name="col0",colhdr="Type"},
{width="10",alignment="-1",col_name="col1",colhdr="Description"},
{width="10",alignment="-1",col_name="col2",colhdr="Title"}],
body=[item={col0="cpus",col1="Listing of all cpus/cores on the system",
col2="CPUs"},
item={col0="files",col1="Listing of all file descriptors",
col2="File descriptors"},
item={col0="modules",col1="Listing of all loaded kernel modules",
col2="Kernel modules"},
item={col0="msg",col1="Listing of all message queues",
col2="Message queues"},
item={col0="processes",col1="Listing of all processes",
col2="Processes"},
item={col0="procgroups",col1="Listing of all process groups",
col2="Process groups"},
item={col0="semaphores",col1="Listing of all semaphores",
col2="Semaphores"},
item={col0="shm",col1="Listing of all shared-memory regions",
col2="Shared-memory regions"},
item={col0="sockets",col1="Listing of all internet-domain sockets",
col2="Sockets"},
item={col0="threads",col1="Listing of all threads",
col2="Threads"}]
gdb
-info-os processes
^done,OSDataTable={nr_rows="190",nr_cols="4",
hdr=[{width="10",alignment="-1",col_name="col0",colhdr="pid"},
{width="10",alignment="-1",col_name="col1",colhdr="user"},
{width="10",alignment="-1",col_name="col2",colhdr="command"},
{width="10",alignment="-1",col_name="col3",colhdr="cores"}],
body=[item={col0="1",col1="root",col2="/sbin/init",col3="0"},
item={col0="2",col1="root",col2="[kthreadd]",col3="1"},
item={col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"},
...
item={col0="26446",col1="stan",col2="bash",col3="0"},
item={col0="28152",col1="stan",col2="bash",col3="1"}]}
(gdb)
(Note that the MI output here includes a '"Title"' column that does
not appear in command-line 'info os'; this column is useful for MI
clients that want to enumerate the types of data, such as in a popup
menu, but is needless clutter on the command line, and 'info os' omits
it.)
The '-add-inferior' Command
---------------------------
Synopsis
--------
-add-inferior
Creates a new inferior (*note Inferiors and Programs::). The created
inferior is not associated with any executable. Such association may be
established with the '-file-exec-and-symbols' command (*note GDB/MI File
Commands::). The command response has a single field, 'inferior', whose
value is the identifier of the thread group corresponding to the new
inferior.
Example
-------
gdb
-add-inferior
^done,inferior="i3"
The '-interpreter-exec' Command
-------------------------------
Synopsis
--------
-interpreter-exec INTERPRETER COMMAND
Execute the specified COMMAND in the given INTERPRETER.
GDB Command
-----------
The corresponding GDB command is 'interpreter-exec'.
Example
-------
(gdb)
-interpreter-exec console "break main"
&"During symbol reading, couldn't parse type; debugger out of date?.\n"
&"During symbol reading, bad structure-type format.\n"
~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
^done
(gdb)
The '-inferior-tty-set' Command
-------------------------------
Synopsis
--------
-inferior-tty-set /dev/pts/1
Set terminal for future runs of the program being debugged.
GDB Command
-----------
The corresponding GDB command is 'set inferior-tty' /dev/pts/1.
Example
-------
(gdb)
-inferior-tty-set /dev/pts/1
^done
(gdb)
The '-inferior-tty-show' Command
--------------------------------
Synopsis
--------
-inferior-tty-show
Show terminal for future runs of program being debugged.
GDB Command
-----------
The corresponding GDB command is 'show inferior-tty'.
Example
-------
(gdb)
-inferior-tty-set /dev/pts/1
^done
(gdb)
-inferior-tty-show
^done,inferior_tty_terminal="/dev/pts/1"
(gdb)
The '-enable-timings' Command
-----------------------------
Synopsis
--------
-enable-timings [yes | no]
Toggle the printing of the wallclock, user and system times for an MI
command as a field in its output. This command is to help frontend
developers optimize the performance of their code. No argument is
equivalent to 'yes'.
GDB Command
-----------
No equivalent.
Example
-------
(gdb)
-enable-timings
^done
(gdb)
-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x080484ed",func="main",file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73",thread-groups=["i1"],
times="0"},
time={wallclock="0.05185",user="0.00800",system="0.00000"}
(gdb)
-enable-timings no
^done
(gdb)
-exec-run
^running
(gdb)
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
frame={addr="0x080484ed",func="main",args=[{name="argc",value="1"},
{name="argv",value="0xbfb60364"}],file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73",arch="i386:x86_64"}
(gdb)
The '-complete' Command
-----------------------
Synopsis
--------
-complete COMMAND
Show a list of completions for partially typed CLI COMMAND.
This command is intended for GDB/MI frontends that cannot use two
separate CLI and MI channels -- for example: because of lack of PTYs
like on Windows or because GDB is used remotely via a SSH connection.
Result
------
The result consists of two or three fields:
'completion'
This field contains the completed COMMAND. If COMMAND has no known
completions, this field is omitted.
'matches'
This field contains a (possibly empty) array of matches. It is
always present.
'max_completions_reached'
This field contains '1' if number of known completions is above
'max-completions' limit (*note Completion::), otherwise it contains
'0'. It is always present.
GDB Command
-----------
The corresponding GDB command is 'complete'.
Example
-------
(gdb)
-complete br
^done,completion="break",
matches=["break","break-range"],
max_completions_reached="0"
(gdb)
-complete "b ma"
^done,completion="b ma",
matches=["b madvise","b main"],max_completions_reached="0"
(gdb)
-complete "b push_b"
^done,completion="b push_back(",
matches=[
"b A::push_back(void*)",
"b std::string::push_back(char)",
"b std::vector<int, std::allocator<int> >::push_back(int&&)"],
max_completions_reached="0"
(gdb)
-complete "nonexist"
^done,matches=[],max_completions_reached="0"
(gdb)

File: gdb.info, Node: Annotations, Next: JIT Interface, Prev: GDB/MI, Up: Top
28 GDB Annotations
******************
This chapter describes annotations in GDB. Annotations were designed to
interface GDB to graphical user interfaces or other similar programs
which want to interact with GDB at a relatively high level.
The annotation mechanism has largely been superseded by GDB/MI (*note
GDB/MI::).
* Menu:
* Annotations Overview:: What annotations are; the general syntax.
* Server Prefix:: Issuing a command without affecting user state.
* Prompting:: Annotations marking GDB's need for input.
* Errors:: Annotations for error messages.
* Invalidation:: Some annotations describe things now invalid.
* Annotations for Running::
Whether the program is running, how it stopped, etc.
* Source Annotations:: Annotations describing source code.

File: gdb.info, Node: Annotations Overview, Next: Server Prefix, Up: Annotations
28.1 What is an Annotation?
===========================
Annotations start with a newline character, two 'control-z' characters,
and the name of the annotation. If there is no additional information
associated with this annotation, the name of the annotation is followed
immediately by a newline. If there is additional information, the name
of the annotation is followed by a space, the additional information,
and a newline. The additional information cannot contain newline
characters.
Any output not beginning with a newline and two 'control-z'
characters denotes literal output from GDB. Currently there is no need
for GDB to output a newline followed by two 'control-z' characters, but
if there was such a need, the annotations could be extended with an
'escape' annotation which means those three characters as output.
The annotation LEVEL, which is specified using the '--annotate'
command line option (*note Mode Options::), controls how much
information GDB prints together with its prompt, values of expressions,
source lines, and other types of output. Level 0 is for no annotations,
level 1 is for use when GDB is run as a subprocess of GNU Emacs, level 3
is the maximum annotation suitable for programs that control GDB, and
level 2 annotations have been made obsolete (*note Limitations of the
Annotation Interface: (annotate)Limitations.).
'set annotate LEVEL'
The GDB command 'set annotate' sets the level of annotations to the
specified LEVEL.
'show annotate'
Show the current annotation level.
This chapter describes level 3 annotations.
A simple example of starting up GDB with annotations is:
$ gdb --annotate=3
GNU gdb 6.0
Copyright 2003 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it
under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty"
for details.
This GDB was configured as "i386-pc-linux-gnu"
^Z^Zpre-prompt
(gdb)
^Z^Zprompt
quit
^Z^Zpost-prompt
$
Here 'quit' is input to GDB; the rest is output from GDB. The three
lines beginning '^Z^Z' (where '^Z' denotes a 'control-z' character) are
annotations; the rest is output from GDB.

File: gdb.info, Node: Server Prefix, Next: Prompting, Prev: Annotations Overview, Up: Annotations
28.2 The Server Prefix
======================
If you prefix a command with 'server ' then it will not affect the
command history, nor will it affect GDB's notion of which command to
repeat if <RET> is pressed on a line by itself. This means that
commands can be run behind a user's back by a front-end in a transparent
manner.
The 'server ' prefix does not affect the recording of values into the
value history; to print a value without recording it into the value
history, use the 'output' command instead of the 'print' command.
Using this prefix also disables confirmation requests (*note
confirmation requests::).

File: gdb.info, Node: Prompting, Next: Errors, Prev: Server Prefix, Up: Annotations
28.3 Annotation for GDB Input
=============================
When GDB prompts for input, it annotates this fact so it is possible to
know when to send output, when the output from a given command is over,
etc.
Different kinds of input each have a different "input type". Each
input type has three annotations: a 'pre-' annotation, which denotes the
beginning of any prompt which is being output, a plain annotation, which
denotes the end of the prompt, and then a 'post-' annotation which
denotes the end of any echo which may (or may not) be associated with
the input. For example, the 'prompt' input type features the following
annotations:
^Z^Zpre-prompt
^Z^Zprompt
^Z^Zpost-prompt
The input types are
'prompt'
When GDB is prompting for a command (the main GDB prompt).
'commands'
When GDB prompts for a set of commands, like in the 'commands'
command. The annotations are repeated for each command which is
input.
'overload-choice'
When GDB wants the user to select between various overloaded
functions.
'query'
When GDB wants the user to confirm a potentially dangerous
operation.
'prompt-for-continue'
When GDB is asking the user to press return to continue. Note:
Don't expect this to work well; instead use 'set height 0' to
disable prompting. This is because the counting of lines is buggy
in the presence of annotations.

File: gdb.info, Node: Errors, Next: Invalidation, Prev: Prompting, Up: Annotations
28.4 Errors
===========
^Z^Zquit
This annotation occurs right before GDB responds to an interrupt.
^Z^Zerror
This annotation occurs right before GDB responds to an error.
Quit and error annotations indicate that any annotations which GDB
was in the middle of may end abruptly. For example, if a
'value-history-begin' annotation is followed by a 'error', one cannot
expect to receive the matching 'value-history-end'. One cannot expect
not to receive it either, however; an error annotation does not
necessarily mean that GDB is immediately returning all the way to the
top level.
A quit or error annotation may be preceded by
^Z^Zerror-begin
Any output between that and the quit or error annotation is the error
message.
Warning messages are not yet annotated.

File: gdb.info, Node: Invalidation, Next: Annotations for Running, Prev: Errors, Up: Annotations
28.5 Invalidation Notices
=========================
The following annotations say that certain pieces of state may have
changed.
'^Z^Zframes-invalid'
The frames (for example, output from the 'backtrace' command) may
have changed.
'^Z^Zbreakpoints-invalid'
The breakpoints may have changed. For example, the user just added
or deleted a breakpoint.

File: gdb.info, Node: Annotations for Running, Next: Source Annotations, Prev: Invalidation, Up: Annotations
28.6 Running the Program
========================
When the program starts executing due to a GDB command such as 'step' or
'continue',
^Z^Zstarting
is output. When the program stops,
^Z^Zstopped
is output. Before the 'stopped' annotation, a variety of annotations
describe how the program stopped.
'^Z^Zexited EXIT-STATUS'
The program exited, and EXIT-STATUS is the exit status (zero for
successful exit, otherwise nonzero).
'^Z^Zsignalled'
The program exited with a signal. After the '^Z^Zsignalled', the
annotation continues:
INTRO-TEXT
^Z^Zsignal-name
NAME
^Z^Zsignal-name-end
MIDDLE-TEXT
^Z^Zsignal-string
STRING
^Z^Zsignal-string-end
END-TEXT
where NAME is the name of the signal, such as 'SIGILL' or
'SIGSEGV', and STRING is the explanation of the signal, such as
'Illegal Instruction' or 'Segmentation fault'. The arguments
INTRO-TEXT, MIDDLE-TEXT, and END-TEXT are for the user's benefit
and have no particular format.
'^Z^Zsignal'
The syntax of this annotation is just like 'signalled', but GDB is
just saying that the program received the signal, not that it was
terminated with it.
'^Z^Zbreakpoint NUMBER'
The program hit breakpoint number NUMBER.
'^Z^Zwatchpoint NUMBER'
The program hit watchpoint number NUMBER.

File: gdb.info, Node: Source Annotations, Prev: Annotations for Running, Up: Annotations
28.7 Displaying Source
======================
The following annotation is used instead of displaying source code:
^Z^Zsource FILENAME:LINE:CHARACTER:MIDDLE:ADDR
where FILENAME is an absolute file name indicating which source file,
LINE is the line number within that file (where 1 is the first line in
the file), CHARACTER is the character position within the file (where 0
is the first character in the file) (for most debug formats this will
necessarily point to the beginning of a line), MIDDLE is 'middle' if
ADDR is in the middle of the line, or 'beg' if ADDR is at the beginning
of the line, and ADDR is the address in the target program associated
with the source which is being displayed. The ADDR is in the form '0x'
followed by one or more lowercase hex digits (note that this does not
depend on the language).

File: gdb.info, Node: JIT Interface, Next: In-Process Agent, Prev: Annotations, Up: Top
29 JIT Compilation Interface
****************************
This chapter documents GDB's "just-in-time" (JIT) compilation interface.
A JIT compiler is a program or library that generates native executable
code at runtime and executes it, usually in order to achieve good
performance while maintaining platform independence.
Programs that use JIT compilation are normally difficult to debug
because portions of their code are generated at runtime, instead of
being loaded from object files, which is where GDB normally finds the
program's symbols and debug information. In order to debug programs
that use JIT compilation, GDB has an interface that allows the program
to register in-memory symbol files with GDB at runtime.
If you are using GDB to debug a program that uses this interface,
then it should work transparently so long as you have not stripped the
binary. If you are developing a JIT compiler, then the interface is
documented in the rest of this chapter. At this time, the only known
client of this interface is the LLVM JIT.
Broadly speaking, the JIT interface mirrors the dynamic loader
interface. The JIT compiler communicates with GDB by writing data into
a global variable and calling a function at a well-known symbol. When
GDB attaches, it reads a linked list of symbol files from the global
variable to find existing code, and puts a breakpoint in the function so
that it can find out about additional code.
* Menu:
* Declarations:: Relevant C struct declarations
* Registering Code:: Steps to register code
* Unregistering Code:: Steps to unregister code
* Custom Debug Info:: Emit debug information in a custom format

File: gdb.info, Node: Declarations, Next: Registering Code, Up: JIT Interface
29.1 JIT Declarations
=====================
These are the relevant struct declarations that a C program should
include to implement the interface:
typedef enum
{
JIT_NOACTION = 0,
JIT_REGISTER_FN,
JIT_UNREGISTER_FN
} jit_actions_t;
struct jit_code_entry
{
struct jit_code_entry *next_entry;
struct jit_code_entry *prev_entry;
const char *symfile_addr;
uint64_t symfile_size;
};
struct jit_descriptor
{
uint32_t version;
/* This type should be jit_actions_t, but we use uint32_t
to be explicit about the bitwidth. */
uint32_t action_flag;
struct jit_code_entry *relevant_entry;
struct jit_code_entry *first_entry;
};
/* GDB puts a breakpoint in this function. */
void __attribute__((noinline)) __jit_debug_register_code() { };
/* Make sure to specify the version statically, because the
debugger may check the version before we can set it. */
struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
If the JIT is multi-threaded, then it is important that the JIT
synchronize any modifications to this global data properly, which can
easily be done by putting a global mutex around modifications to these
structures.

File: gdb.info, Node: Registering Code, Next: Unregistering Code, Prev: Declarations, Up: JIT Interface
29.2 Registering Code
=====================
To register code with GDB, the JIT should follow this protocol:
* Generate an object file in memory with symbols and other desired
debug information. The file must include the virtual addresses of
the sections.
* Create a code entry for the file, which gives the start and size of
the symbol file.
* Add it to the linked list in the JIT descriptor.
* Point the relevant_entry field of the descriptor at the entry.
* Set 'action_flag' to 'JIT_REGISTER' and call
'__jit_debug_register_code'.
When GDB is attached and the breakpoint fires, GDB uses the
'relevant_entry' pointer so it doesn't have to walk the list looking for
new code. However, the linked list must still be maintained in order to
allow GDB to attach to a running process and still find the symbol
files.

File: gdb.info, Node: Unregistering Code, Next: Custom Debug Info, Prev: Registering Code, Up: JIT Interface
29.3 Unregistering Code
=======================
If code is freed, then the JIT should use the following protocol:
* Remove the code entry corresponding to the code from the linked
list.
* Point the 'relevant_entry' field of the descriptor at the code
entry.
* Set 'action_flag' to 'JIT_UNREGISTER' and call
'__jit_debug_register_code'.
If the JIT frees or recompiles code without unregistering it, then
GDB and the JIT will leak the memory used for the associated symbol
files.

File: gdb.info, Node: Custom Debug Info, Prev: Unregistering Code, Up: JIT Interface
29.4 Custom Debug Info
======================
Generating debug information in platform-native file formats (like ELF
or COFF) may be an overkill for JIT compilers; especially if all the
debug info is used for is displaying a meaningful backtrace. The issue
can be resolved by having the JIT writers decide on a debug info format
and also provide a reader that parses the debug info generated by the
JIT compiler. This section gives a brief overview on writing such a
parser. More specific details can be found in the source file
'gdb/jit-reader.in', which is also installed as a header at
'INCLUDEDIR/gdb/jit-reader.h' for easy inclusion.
The reader is implemented as a shared object (so this functionality
is not available on platforms which don't allow loading shared objects
at runtime). Two GDB commands, 'jit-reader-load' and
'jit-reader-unload' are provided, to be used to load and unload the
readers from a preconfigured directory. Once loaded, the shared object
is used the parse the debug information emitted by the JIT compiler.
* Menu:
* Using JIT Debug Info Readers:: How to use supplied readers correctly
* Writing JIT Debug Info Readers:: Creating a debug-info reader

File: gdb.info, Node: Using JIT Debug Info Readers, Next: Writing JIT Debug Info Readers, Up: Custom Debug Info
29.4.1 Using JIT Debug Info Readers
-----------------------------------
Readers can be loaded and unloaded using the 'jit-reader-load' and
'jit-reader-unload' commands.
'jit-reader-load READER'
Load the JIT reader named READER, which is a shared object
specified as either an absolute or a relative file name. In the
latter case, GDB will try to load the reader from a pre-configured
directory, usually 'LIBDIR/gdb/' on a UNIX system (here LIBDIR is
the system library directory, often '/usr/local/lib').
Only one reader can be active at a time; trying to load a second
reader when one is already loaded will result in GDB reporting an
error. A new JIT reader can be loaded by first unloading the
current one using 'jit-reader-unload' and then invoking
'jit-reader-load'.
'jit-reader-unload'
Unload the currently loaded JIT reader.

File: gdb.info, Node: Writing JIT Debug Info Readers, Prev: Using JIT Debug Info Readers, Up: Custom Debug Info
29.4.2 Writing JIT Debug Info Readers
-------------------------------------
As mentioned, a reader is essentially a shared object conforming to a
certain ABI. This ABI is described in 'jit-reader.h'.
'jit-reader.h' defines the structures, macros and functions required
to write a reader. It is installed (along with GDB), in
'INCLUDEDIR/gdb' where INCLUDEDIR is the system include directory.
Readers need to be released under a GPL compatible license. A reader
can be declared as released under such a license by placing the macro
'GDB_DECLARE_GPL_COMPATIBLE_READER' in a source file.
The entry point for readers is the symbol 'gdb_init_reader', which is
expected to be a function with the prototype
extern struct gdb_reader_funcs *gdb_init_reader (void);
'struct gdb_reader_funcs' contains a set of pointers to callback
functions. These functions are executed to read the debug info
generated by the JIT compiler ('read'), to unwind stack frames
('unwind') and to create canonical frame IDs ('get_frame_id'). It also
has a callback that is called when the reader is being unloaded
('destroy'). The struct looks like this
struct gdb_reader_funcs
{
/* Must be set to GDB_READER_INTERFACE_VERSION. */
int reader_version;
/* For use by the reader. */
void *priv_data;
gdb_read_debug_info *read;
gdb_unwind_frame *unwind;
gdb_get_frame_id *get_frame_id;
gdb_destroy_reader *destroy;
};
The callbacks are provided with another set of callbacks by GDB to do
their job. For 'read', these callbacks are passed in a 'struct
gdb_symbol_callbacks' and for 'unwind' and 'get_frame_id', in a 'struct
gdb_unwind_callbacks'. 'struct gdb_symbol_callbacks' has callbacks to
create new object files and new symbol tables inside those object files.
'struct gdb_unwind_callbacks' has callbacks to read registers off the
current frame and to write out the values of the registers in the
previous frame. Both have a callback ('target_read') to read bytes off
the target's address space.

File: gdb.info, Node: In-Process Agent, Next: GDB Bugs, Prev: JIT Interface, Up: Top
30 In-Process Agent
*******************
The traditional debugging model is conceptually low-speed, but works
fine, because most bugs can be reproduced in debugging-mode execution.
However, as multi-core or many-core processors are becoming mainstream,
and multi-threaded programs become more and more popular, there should
be more and more bugs that only manifest themselves at normal-mode
execution, for example, thread races, because debugger's interference
with the program's timing may conceal the bugs. On the other hand, in
some applications, it is not feasible for the debugger to interrupt the
program's execution long enough for the developer to learn anything
helpful about its behavior. If the program's correctness depends on its
real-time behavior, delays introduced by a debugger might cause the
program to fail, even when the code itself is correct. It is useful to
be able to observe the program's behavior without interrupting it.
Therefore, traditional debugging model is too intrusive to reproduce
some bugs. In order to reduce the interference with the program, we can
reduce the number of operations performed by debugger. The "In-Process
Agent", a shared library, is running within the same process with
inferior, and is able to perform some debugging operations itself. As a
result, debugger is only involved when necessary, and performance of
debugging can be improved accordingly. Note that interference with
program can be reduced but can't be removed completely, because the
in-process agent will still stop or slow down the program.
The in-process agent can interpret and execute Agent Expressions
(*note Agent Expressions::) during performing debugging operations. The
agent expressions can be used for different purposes, such as collecting
data in tracepoints, and condition evaluation in breakpoints.
You can control whether the in-process agent is used as an aid for
debugging with the following commands:
'set agent on'
Causes the in-process agent to perform some operations on behalf of
the debugger. Just which operations requested by the user will be
done by the in-process agent depends on the its capabilities. For
example, if you request to evaluate breakpoint conditions in the
in-process agent, and the in-process agent has such capability as
well, then breakpoint conditions will be evaluated in the
in-process agent.
'set agent off'
Disables execution of debugging operations by the in-process agent.
All of the operations will be performed by GDB.
'show agent'
Display the current setting of execution of debugging operations by
the in-process agent.
* Menu:
* In-Process Agent Protocol::

File: gdb.info, Node: In-Process Agent Protocol, Up: In-Process Agent
30.1 In-Process Agent Protocol
==============================
The in-process agent is able to communicate with both GDB and GDBserver
(*note In-Process Agent::). This section documents the protocol used
for communications between GDB or GDBserver and the IPA. In general, GDB
or GDBserver sends commands (*note IPA Protocol Commands::) and data to
in-process agent, and then in-process agent replies back with the return
result of the command, or some other information. The data sent to
in-process agent is composed of primitive data types, such as 4-byte or
8-byte type, and composite types, which are called objects (*note IPA
Protocol Objects::).
* Menu:
* IPA Protocol Objects::
* IPA Protocol Commands::

File: gdb.info, Node: IPA Protocol Objects, Next: IPA Protocol Commands, Up: In-Process Agent Protocol
30.1.1 IPA Protocol Objects
---------------------------
The commands sent to and results received from agent may contain some
complex data types called "objects".
The in-process agent is running on the same machine with GDB or
GDBserver, so it doesn't have to handle as much differences between two
ends as remote protocol (*note Remote Protocol::) tries to handle.
However, there are still some differences of two ends in two processes:
1. word size. On some 64-bit machines, GDB or GDBserver can be
compiled as a 64-bit executable, while in-process agent is a 32-bit
one.
2. ABI. Some machines may have multiple types of ABI, GDB or GDBserver
is compiled with one, and in-process agent is compiled with the
other one.
Here are the IPA Protocol Objects:
1. agent expression object. It represents an agent expression (*note
Agent Expressions::).
2. tracepoint action object. It represents a tracepoint action (*note
Tracepoint Action Lists: Tracepoint Actions.) to collect registers,
memory, static trace data and to evaluate expression.
3. tracepoint object. It represents a tracepoint (*note
Tracepoints::).
The following table describes important attributes of each IPA
protocol object:
Name Size Description
---------------------------------------------------------------------------
_agent expression
object_
length 4 length of bytes code
byte code LENGTH contents of byte code
_tracepoint action
for collecting
memory_
'M' 1 type of tracepoint action
addr 8 if BASEREG is '-1', ADDR is the
address of the lowest byte to
collect, otherwise ADDR is the
offset of BASEREG for memory
collecting.
len 8 length of memory for collecting
basereg 4 the register number containing the
starting memory address for
collecting.
_tracepoint action
for collecting
registers_
'R' 1 type of tracepoint action
_tracepoint action
for collecting
static trace data_
'L' 1 type of tracepoint action
_tracepoint action
for expression
evaluation_
'X' 1 type of tracepoint action
agent expression length of *note agent expression object::
_tracepoint object_
number 4 number of tracepoint
address 8 address of tracepoint inserted on
type 4 type of tracepoint
enabled 1 enable or disable of tracepoint
step_count 8 step
pass_count 8 pass
numactions 4 number of tracepoint actions
hit count 8 hit count
trace frame usage 8 trace frame usage
compiled_cond 8 compiled condition
orig_size 8 orig size
condition 4 if zero if condition is NULL,
condition is otherwise is
NULL *note agent expression object::
otherwise
length of
*note agent expression object::
actions variable numactions number of
*note tracepoint action object::

File: gdb.info, Node: IPA Protocol Commands, Prev: IPA Protocol Objects, Up: In-Process Agent Protocol
30.1.2 IPA Protocol Commands
----------------------------
The spaces in each command are delimiters to ease reading this commands
specification. They don't exist in real commands.
'FastTrace:TRACEPOINT_OBJECT GDB_JUMP_PAD_HEAD'
Installs a new fast tracepoint described by TRACEPOINT_OBJECT
(*note tracepoint object::). The GDB_JUMP_PAD_HEAD, 8-byte long,
is the head of "jumppad", which is used to jump to data collection
routine in IPA finally.
Replies:
'OK TARGET_ADDRESS GDB_JUMP_PAD_HEAD FJUMP_SIZE FJUMP'
TARGET_ADDRESS is address of tracepoint in the inferior. The
GDB_JUMP_PAD_HEAD is updated head of jumppad. Both of
TARGET_ADDRESS and GDB_JUMP_PAD_HEAD are 8-byte long. The
FJUMP contains a sequence of instructions jump to jumppad
entry. The FJUMP_SIZE, 4-byte long, is the size of FJUMP.
'E NN'
for an error
'close'
Closes the in-process agent. This command is sent when GDB or
GDBserver is about to kill inferiors.
'qTfSTM'
*Note qTfSTM::.
'qTsSTM'
*Note qTsSTM::.
'qTSTMat'
*Note qTSTMat::.
'probe_marker_at:ADDRESS'
Asks in-process agent to probe the marker at ADDRESS.
Replies:
'E NN'
for an error
'unprobe_marker_at:ADDRESS'
Asks in-process agent to unprobe the marker at ADDRESS.

File: gdb.info, Node: GDB Bugs, Next: Command Line Editing, Prev: In-Process Agent, Up: Top
31 Reporting Bugs in GDB
************************
Your bug reports play an essential role in making GDB reliable.
Reporting a bug may help you by bringing a solution to your problem,
or it may not. But in any case the principal function of a bug report
is to help the entire community by making the next version of GDB work
better. Bug reports are your contribution to the maintenance of GDB.
In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.
* Menu:
* Bug Criteria:: Have you found a bug?
* Bug Reporting:: How to report bugs

File: gdb.info, Node: Bug Criteria, Next: Bug Reporting, Up: GDB Bugs
31.1 Have You Found a Bug?
==========================
If you are not sure whether you have found a bug, here are some
guidelines:
* If the debugger gets a fatal signal, for any input whatever, that
is a GDB bug. Reliable debuggers never crash.
* If GDB produces an error message for valid input, that is a bug.
(Note that if you're cross debugging, the problem may also be
somewhere in the connection to the target.)
* If GDB does not produce an error message for invalid input, that is
a bug. However, you should note that your idea of "invalid input"
might be our idea of "an extension" or "support for traditional
practice".
* If you are an experienced user of debugging tools, your suggestions
for improvement of GDB are welcome in any case.

File: gdb.info, Node: Bug Reporting, Prev: Bug Criteria, Up: GDB Bugs
31.2 How to Report Bugs
=======================
A number of companies and individuals offer support for GNU products.
If you obtained GDB from a support organization, we recommend you
contact that organization first.
You can find contact information for many support companies and
individuals in the file 'etc/SERVICE' in the GNU Emacs distribution.
In any event, we also recommend that you submit bug reports for GDB.
The preferred method is to submit them directly using GDB's Bugs web
page (http://www.gnu.org/software/gdb/bugs/). Alternatively, the e-mail
gateway <bug-gdb@gnu.org> can be used.
*Do not send bug reports to 'info-gdb', or to 'help-gdb', or to any
newsgroups.* Most users of GDB do not want to receive bug reports.
Those that do have arranged to receive 'bug-gdb'.
The mailing list 'bug-gdb' has a newsgroup 'gnu.gdb.bug' which serves
as a repeater. The mailing list and the newsgroup carry exactly the
same messages. Often people think of posting bug reports to the
newsgroup instead of mailing them. This appears to work, but it has one
problem which can be crucial: a newsgroup posting often lacks a mail
path back to the sender. Thus, if we need to ask for more information,
we may be unable to reach you. For this reason, it is better to send
bug reports to the mailing list.
The fundamental principle of reporting bugs usefully is this: *report
all the facts*. If you are not sure whether to state a fact or leave it
out, state it!
Often people omit facts because they think they know what causes the
problem and assume that some details do not matter. Thus, you might
assume that the name of the variable you use in an example does not
matter. Well, probably it does not, but one cannot be sure. Perhaps
the bug is a stray memory reference which happens to fetch from the
location where that name is stored in memory; perhaps, if the name were
different, the contents of that location would fool the debugger into
doing the right thing despite the bug. Play it safe and give a
specific, complete example. That is the easiest thing for you to do,
and the most helpful.
Keep in mind that the purpose of a bug report is to enable us to fix
the bug. It may be that the bug has been reported previously, but
neither you nor we can know that unless your bug report is complete and
self-contained.
Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?" Those bug reports are useless, and we urge everyone to _refuse
to respond to them_ except to chide the sender to report bugs properly.
To enable us to fix the bug, you should include all these things:
* The version of GDB. GDB announces it if you start with no
arguments; you can also print it at any time using 'show version'.
Without this, we will not know whether there is any point in
looking for the bug in the current version of GDB.
* The type of machine you are using, and the operating system name
and version number.
* The details of the GDB build-time configuration. GDB shows these
details if you invoke it with the '--configuration' command-line
option, or if you type 'show configuration' at GDB's prompt.
* What compiler (and its version) was used to compile GDB--e.g.
"gcc-2.8.1".
* What compiler (and its version) was used to compile the program you
are debugging--e.g. "gcc-2.8.1", or "HP92453-01 A.10.32.03 HP C
Compiler". For GCC, you can say 'gcc --version' to get this
information; for other compilers, see the documentation for those
compilers.
* The command arguments you gave the compiler to compile your example
and observe the bug. For example, did you use '-O'? To guarantee
you will not omit something important, list them all. A copy of
the Makefile (or the output from make) is sufficient.
If we were to try to guess the arguments, we would probably guess
wrong and then we might not encounter the bug.
* A complete input script, and all necessary source files, that will
reproduce the bug.
* A description of what behavior you observe that you believe is
incorrect. For example, "It gets a fatal signal."
Of course, if the bug is that GDB gets a fatal signal, then we will
certainly notice it. But if the bug is incorrect output, we might
not notice unless it is glaringly wrong. You might as well not
give us a chance to make a mistake.
Even if the problem you experience is a fatal signal, you should
still say so explicitly. Suppose something strange is going on,
such as, your copy of GDB is out of synch, or you have encountered
a bug in the C library on your system. (This has happened!) Your
copy might crash and ours would not. If you told us to expect a
crash, then when ours fails to crash, we would know that the bug
was not happening for us. If you had not told us to expect a
crash, then we would not be able to draw any conclusion from our
observations.
To collect all this information, you can use a session recording
program such as 'script', which is available on many Unix systems.
Just run your GDB session inside 'script' and then include the
'typescript' file with your bug report.
Another way to record a GDB session is to run GDB inside Emacs and
then save the entire buffer to a file.
* If you wish to suggest changes to the GDB source, send us context
diffs. If you even discuss something in the GDB source, refer to
it by context, not by line number.
The line numbers in our development sources will not match those in
your sources. Your line numbers would convey no useful information
to us.
Here are some things that are not necessary:
* A description of the envelope of the bug.
Often people who encounter a bug spend a lot of time investigating
which changes to the input file will make the bug go away and which
changes will not affect it.
This is often time consuming and not very useful, because the way
we will find the bug is by running a single example under the
debugger with breakpoints, not by pure deduction from a series of
examples. We recommend that you save your time for something else.
Of course, if you can find a simpler example to report _instead_ of
the original one, that is a convenience for us. Errors in the
output will be easier to spot, running under the debugger will take
less time, and so on.
However, simplification is not vital; if you do not want to do
this, report the bug anyway and send us the entire test case you
used.
* A patch for the bug.
A patch for the bug does help us if it is a good one. But do not
omit the necessary information, such as the test case, on the
assumption that a patch is all we need. We might see problems with
your patch and decide to fix the problem another way, or we might
not understand it at all.
Sometimes with a program as complicated as GDB it is very hard to
construct an example that will make the program follow a certain
path through the code. If you do not send us the example, we will
not be able to construct one, so we will not be able to verify that
the bug is fixed.
And if we cannot understand what bug you are trying to fix, or why
your patch should be an improvement, we will not install it. A
test case will help us to understand.
* A guess about what the bug is or what it depends on.
Such guesses are usually wrong. Even we cannot guess right about
such things without first using the debugger to find the facts.

File: gdb.info, Node: Command Line Editing, Next: Using History Interactively, Prev: GDB Bugs, Up: Top
32 Command Line Editing
***********************
This chapter describes the basic features of the GNU command line
editing interface.
* Menu:
* Introduction and Notation:: Notation used in this text.
* Readline Interaction:: The minimum set of commands for editing a line.
* Readline Init File:: Customizing Readline from a user's view.
* Bindable Readline Commands:: A description of most of the Readline commands
available for binding
* Readline vi Mode:: A short description of how to make Readline
behave like the vi editor.

File: gdb.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing
32.1 Introduction to Line Editing
=================================
The following paragraphs describe the notation used to represent
keystrokes.
The text 'C-k' is read as 'Control-K' and describes the character
produced when the <k> key is pressed while the Control key is depressed.
The text 'M-k' is read as 'Meta-K' and describes the character
produced when the Meta key (if you have one) is depressed, and the <k>
key is pressed. The Meta key is labeled <ALT> on many keyboards. On
keyboards with two keys labeled <ALT> (usually to either side of the
space bar), the <ALT> on the left side is generally set to work as a
Meta key. The <ALT> key on the right may also be configured to work as
a Meta key or may be configured as some other modifier, such as a
Compose key for typing accented characters.
If you do not have a Meta or <ALT> key, or another key working as a
Meta key, the identical keystroke can be generated by typing <ESC>
_first_, and then typing <k>. Either process is known as "metafying"
the <k> key.
The text 'M-C-k' is read as 'Meta-Control-k' and describes the
character produced by "metafying" 'C-k'.
In addition, several keys have their own names. Specifically, <DEL>,
<ESC>, <LFD>, <SPC>, <RET>, and <TAB> all stand for themselves when seen
in this text, or in an init file (*note Readline Init File::). If your
keyboard lacks a <LFD> key, typing <C-j> will produce the desired
character. The <RET> key may be labeled <Return> or <Enter> on some
keyboards.

File: gdb.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing
32.2 Readline Interaction
=========================
Often during an interactive session you type in a long line of text,
only to notice that the first word on the line is misspelled. The
Readline library gives you a set of commands for manipulating the text
as you type it in, allowing you to just fix your typo, and not forcing
you to retype the majority of the line. Using these editing commands,
you move the cursor to the place that needs correction, and delete or
insert the text of the corrections. Then, when you are satisfied with
the line, you simply press <RET>. You do not have to be at the end of
the line to press <RET>; the entire line is accepted regardless of the
location of the cursor within the line.
* Menu:
* Readline Bare Essentials:: The least you need to know about Readline.
* Readline Movement Commands:: Moving about the input line.
* Readline Killing Commands:: How to delete text, and how to get it back!
* Readline Arguments:: Giving numeric arguments to commands.
* Searching:: Searching through previous lines.

File: gdb.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction
32.2.1 Readline Bare Essentials
-------------------------------
In order to enter characters into the line, simply type them. The typed
character appears where the cursor was, and then the cursor moves one
space to the right. If you mistype a character, you can use your erase
character to back up and delete the mistyped character.
Sometimes you may mistype a character, and not notice the error until
you have typed several other characters. In that case, you can type
'C-b' to move the cursor to the left, and then correct your mistake.
Afterwards, you can move the cursor to the right with 'C-f'.
When you add text in the middle of a line, you will notice that
characters to the right of the cursor are 'pushed over' to make room for
the text that you have inserted. Likewise, when you delete text behind
the cursor, characters to the right of the cursor are 'pulled back' to
fill in the blank space created by the removal of the text. A list of
the bare essentials for editing the text of an input line follows.
'C-b'
Move back one character.
'C-f'
Move forward one character.
<DEL> or <Backspace>
Delete the character to the left of the cursor.
'C-d'
Delete the character underneath the cursor.
Printing characters
Insert the character into the line at the cursor.
'C-_' or 'C-x C-u'
Undo the last editing command. You can undo all the way back to an
empty line.
(Depending on your configuration, the <Backspace> key be set to delete
the character to the left of the cursor and the <DEL> key set to delete
the character underneath the cursor, like 'C-d', rather than the
character to the left of the cursor.)

File: gdb.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction
32.2.2 Readline Movement Commands
---------------------------------
The above table describes the most basic keystrokes that you need in
order to do editing of the input line. For your convenience, many other
commands have been added in addition to 'C-b', 'C-f', 'C-d', and <DEL>.
Here are some commands for moving more rapidly about the line.
'C-a'
Move to the start of the line.
'C-e'
Move to the end of the line.
'M-f'
Move forward a word, where a word is composed of letters and
digits.
'M-b'
Move backward a word.
'C-l'
Clear the screen, reprinting the current line at the top.
Notice how 'C-f' moves forward a character, while 'M-f' moves forward
a word. It is a loose convention that control keystrokes operate on
characters while meta keystrokes operate on words.

File: gdb.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction
32.2.3 Readline Killing Commands
--------------------------------
"Killing" text means to delete the text from the line, but to save it
away for later use, usually by "yanking" (re-inserting) it back into the
line. ('Cut' and 'paste' are more recent jargon for 'kill' and 'yank'.)
If the description for a command says that it 'kills' text, then you
can be sure that you can get the text back in a different (or the same)
place later.
When you use a kill command, the text is saved in a "kill-ring". Any
number of consecutive kills save all of the killed text together, so
that when you yank it back, you get it all. The kill ring is not line
specific; the text that you killed on a previously typed line is
available to be yanked back later, when you are typing another line.
Here is the list of commands for killing text.
'C-k'
Kill the text from the current cursor position to the end of the
line.
'M-d'
Kill from the cursor to the end of the current word, or, if between
words, to the end of the next word. Word boundaries are the same
as those used by 'M-f'.
'M-<DEL>'
Kill from the cursor the start of the current word, or, if between
words, to the start of the previous word. Word boundaries are the
same as those used by 'M-b'.
'C-w'
Kill from the cursor to the previous whitespace. This is different
than 'M-<DEL>' because the word boundaries differ.
Here is how to "yank" the text back into the line. Yanking means to
copy the most-recently-killed text from the kill buffer.
'C-y'
Yank the most recently killed text back into the buffer at the
cursor.
'M-y'
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is 'C-y' or 'M-y'.

File: gdb.info, Node: Readline Arguments, Next: Searching, Prev: Readline Killing Commands, Up: Readline Interaction
32.2.4 Readline Arguments
-------------------------
You can pass numeric arguments to Readline commands. Sometimes the
argument acts as a repeat count, other times it is the sign of the
argument that is significant. If you pass a negative argument to a
command which normally acts in a forward direction, that command will
act in a backward direction. For example, to kill text back to the
start of the line, you might type 'M-- C-k'.
The general way to pass numeric arguments to a command is to type
meta digits before the command. If the first 'digit' typed is a minus
sign ('-'), then the sign of the argument will be negative. Once you
have typed one meta digit to get the argument started, you can type the
remainder of the digits, and then the command. For example, to give the
'C-d' command an argument of 10, you could type 'M-1 0 C-d', which will
delete the next ten characters on the input line.

File: gdb.info, Node: Searching, Prev: Readline Arguments, Up: Readline Interaction
32.2.5 Searching for Commands in the History
--------------------------------------------
Readline provides commands for searching through the command history for
lines containing a specified string. There are two search modes:
"incremental" and "non-incremental".
Incremental searches begin before the user has finished typing the
search string. As each character of the search string is typed,
Readline displays the next entry from the history matching the string
typed so far. An incremental search requires only as many characters as
needed to find the desired history entry. To search backward in the
history for a particular string, type 'C-r'. Typing 'C-s' searches
forward through the history. The characters present in the value of the
'isearch-terminators' variable are used to terminate an incremental
search. If that variable has not been assigned a value, the <ESC> and
'C-J' characters will terminate an incremental search. 'C-g' will abort
an incremental search and restore the original line. When the search is
terminated, the history entry containing the search string becomes the
current line.
To find other matching entries in the history list, type 'C-r' or
'C-s' as appropriate. This will search backward or forward in the
history for the next entry matching the search string typed so far. Any
other key sequence bound to a Readline command will terminate the search
and execute that command. For instance, a <RET> will terminate the
search and accept the line, thereby executing the command from the
history list. A movement command will terminate the search, make the
last line found the current line, and begin editing.
Readline remembers the last incremental search string. If two 'C-r's
are typed without any intervening characters defining a new search
string, any remembered search string is used.
Non-incremental searches read the entire search string before
starting to search for matching history lines. The search string may be
typed by the user or be part of the contents of the current line.

File: gdb.info, Node: Readline Init File, Next: Bindable Readline Commands, Prev: Readline Interaction, Up: Command Line Editing
32.3 Readline Init File
=======================
Although the Readline library comes with a set of Emacs-like keybindings
installed by default, it is possible to use a different set of
keybindings. Any user can customize programs that use Readline by
putting commands in an "inputrc" file, conventionally in his home
directory. The name of this file is taken from the value of the
environment variable 'INPUTRC'. If that variable is unset, the default
is '~/.inputrc'. If that file does not exist or cannot be read, the
ultimate default is '/etc/inputrc'.
When a program which uses the Readline library starts up, the init
file is read, and the key bindings are set.
In addition, the 'C-x C-r' command re-reads this init file, thus
incorporating any changes that you might have made to it.
* Menu:
* Readline Init File Syntax:: Syntax for the commands in the inputrc file.
* Conditional Init Constructs:: Conditional key bindings in the inputrc file.
* Sample Init File:: An example inputrc file.

File: gdb.info, Node: Readline Init File Syntax, Next: Conditional Init Constructs, Up: Readline Init File
32.3.1 Readline Init File Syntax
--------------------------------
There are only a few basic constructs allowed in the Readline init file.
Blank lines are ignored. Lines beginning with a '#' are comments.
Lines beginning with a '$' indicate conditional constructs (*note
Conditional Init Constructs::). Other lines denote variable settings
and key bindings.
Variable Settings
You can modify the run-time behavior of Readline by altering the
values of variables in Readline using the 'set' command within the
init file. The syntax is simple:
set VARIABLE VALUE
Here, for example, is how to change from the default Emacs-like key
binding to use 'vi' line editing commands:
set editing-mode vi
Variable names and values, where appropriate, are recognized
without regard to case. Unrecognized variable names are ignored.
Boolean variables (those that can be set to on or off) are set to
on if the value is null or empty, ON (case-insensitive), or 1. Any
other value results in the variable being set to off.
A great deal of run-time behavior is changeable with the following
variables.
'bell-style'
Controls what happens when Readline wants to ring the terminal
bell. If set to 'none', Readline never rings the bell. If
set to 'visible', Readline uses a visible bell if one is
available. If set to 'audible' (the default), Readline
attempts to ring the terminal's bell.
'bind-tty-special-chars'
If set to 'on' (the default), Readline attempts to bind the
control characters treated specially by the kernel's terminal
driver to their Readline equivalents.
'blink-matching-paren'
If set to 'on', Readline attempts to briefly move the cursor
to an opening parenthesis when a closing parenthesis is
inserted. The default is 'off'.
'colored-completion-prefix'
If set to 'on', when listing completions, Readline displays
the common prefix of the set of possible completions using a
different color. The color definitions are taken from the
value of the 'LS_COLORS' environment variable. The default is
'off'.
'colored-stats'
If set to 'on', Readline displays possible completions using
different colors to indicate their file type. The color
definitions are taken from the value of the 'LS_COLORS'
environment variable. The default is 'off'.
'comment-begin'
The string to insert at the beginning of the line when the
'insert-comment' command is executed. The default value is
'"#"'.
'completion-display-width'
The number of screen columns used to display possible matches
when performing completion. The value is ignored if it is
less than 0 or greater than the terminal screen width. A
value of 0 will cause matches to be displayed one per line.
The default value is -1.
'completion-ignore-case'
If set to 'on', Readline performs filename matching and
completion in a case-insensitive fashion. The default value
is 'off'.
'completion-map-case'
If set to 'on', and COMPLETION-IGNORE-CASE is enabled,
Readline treats hyphens ('-') and underscores ('_') as
equivalent when performing case-insensitive filename matching
and completion. The default value is 'off'.
'completion-prefix-display-length'
The length in characters of the common prefix of a list of
possible completions that is displayed without modification.
When set to a value greater than zero, common prefixes longer
than this value are replaced with an ellipsis when displaying
possible completions.
'completion-query-items'
The number of possible completions that determines when the
user is asked whether the list of possibilities should be
displayed. If the number of possible completions is greater
than this value, Readline will ask the user whether or not he
wishes to view them; otherwise, they are simply listed. This
variable must be set to an integer value greater than or equal
to 0. A negative value means Readline should never ask. The
default limit is '100'.
'convert-meta'
If set to 'on', Readline will convert characters with the
eighth bit set to an ASCII key sequence by stripping the
eighth bit and prefixing an <ESC> character, converting them
to a meta-prefixed key sequence. The default value is 'on',
but will be set to 'off' if the locale is one that contains
eight-bit characters.
'disable-completion'
If set to 'On', Readline will inhibit word completion.
Completion characters will be inserted into the line as if
they had been mapped to 'self-insert'. The default is 'off'.
'echo-control-characters'
When set to 'on', on operating systems that indicate they
support it, readline echoes a character corresponding to a
signal generated from the keyboard. The default is 'on'.
'editing-mode'
The 'editing-mode' variable controls which default set of key
bindings is used. By default, Readline starts up in Emacs
editing mode, where the keystrokes are most similar to Emacs.
This variable can be set to either 'emacs' or 'vi'.
'emacs-mode-string'
If the SHOW-MODE-IN-PROMPT variable is enabled, this string is
displayed immediately before the last line of the primary
prompt when emacs editing mode is active. The value is
expanded like a key binding, so the standard set of meta- and
control prefixes and backslash escape sequences is available.
Use the '\1' and '\2' escapes to begin and end sequences of
non-printing characters, which can be used to embed a terminal
control sequence into the mode string. The default is '@'.
'enable-bracketed-paste'
When set to 'On', Readline will configure the terminal in a
way that will enable it to insert each paste into the editing
buffer as a single string of characters, instead of treating
each character as if it had been read from the keyboard. This
can prevent pasted characters from being interpreted as
editing commands. The default is 'off'.
'enable-keypad'
When set to 'on', Readline will try to enable the application
keypad when it is called. Some systems need this to enable
the arrow keys. The default is 'off'.
'enable-meta-key'
When set to 'on', Readline will try to enable any meta
modifier key the terminal claims to support when it is called.
On many terminals, the meta key is used to send eight-bit
characters. The default is 'on'.
'expand-tilde'
If set to 'on', tilde expansion is performed when Readline
attempts word completion. The default is 'off'.
'history-preserve-point'
If set to 'on', the history code attempts to place the point
(the current cursor position) at the same location on each
history line retrieved with 'previous-history' or
'next-history'. The default is 'off'.
'history-size'
Set the maximum number of history entries saved in the history
list. If set to zero, any existing history entries are
deleted and no new entries are saved. If set to a value less
than zero, the number of history entries is not limited. By
default, the number of history entries is not limited. If an
attempt is made to set HISTORY-SIZE to a non-numeric value,
the maximum number of history entries will be set to 500.
'horizontal-scroll-mode'
This variable can be set to either 'on' or 'off'. Setting it
to 'on' means that the text of the lines being edited will
scroll horizontally on a single screen line when they are
longer than the width of the screen, instead of wrapping onto
a new screen line. By default, this variable is set to 'off'.
'input-meta'
If set to 'on', Readline will enable eight-bit input (it will
not clear the eighth bit in the characters it reads),
regardless of what the terminal claims it can support. The
default value is 'off', but Readline will set it to 'on' if
the locale contains eight-bit characters. The name
'meta-flag' is a synonym for this variable.
'isearch-terminators'
The string of characters that should terminate an incremental
search without subsequently executing the character as a
command (*note Searching::). If this variable has not been
given a value, the characters <ESC> and 'C-J' will terminate
an incremental search.
'keymap'
Sets Readline's idea of the current keymap for key binding
commands. Built-in 'keymap' names are 'emacs',
'emacs-standard', 'emacs-meta', 'emacs-ctlx', 'vi', 'vi-move',
'vi-command', and 'vi-insert'. 'vi' is equivalent to
'vi-command' ('vi-move' is also a synonym); 'emacs' is
equivalent to 'emacs-standard'. Applications may add
additional names. The default value is 'emacs'. The value of
the 'editing-mode' variable also affects the default keymap.
'keyseq-timeout'
Specifies the duration Readline will wait for a character when
reading an ambiguous key sequence (one that can form a
complete key sequence using the input read so far, or can take
additional input to complete a longer key sequence). If no
input is received within the timeout, Readline will use the
shorter but complete key sequence. Readline uses this value
to determine whether or not input is available on the current
input source ('rl_instream' by default). The value is
specified in milliseconds, so a value of 1000 means that
Readline will wait one second for additional input. If this
variable is set to a value less than or equal to zero, or to a
non-numeric value, Readline will wait until another key is
pressed to decide which key sequence to complete. The default
value is '500'.
'mark-directories'
If set to 'on', completed directory names have a slash
appended. The default is 'on'.
'mark-modified-lines'
This variable, when set to 'on', causes Readline to display an
asterisk ('*') at the start of history lines which have been
modified. This variable is 'off' by default.
'mark-symlinked-directories'
If set to 'on', completed names which are symbolic links to
directories have a slash appended (subject to the value of
'mark-directories'). The default is 'off'.
'match-hidden-files'
This variable, when set to 'on', causes Readline to match
files whose names begin with a '.' (hidden files) when
performing filename completion. If set to 'off', the leading
'.' must be supplied by the user in the filename to be
completed. This variable is 'on' by default.
'menu-complete-display-prefix'
If set to 'on', menu completion displays the common prefix of
the list of possible completions (which may be empty) before
cycling through the list. The default is 'off'.
'output-meta'
If set to 'on', Readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence. The default is 'off', but Readline will set it to
'on' if the locale contains eight-bit characters.
'page-completions'
If set to 'on', Readline uses an internal 'more'-like pager to
display a screenful of possible completions at a time. This
variable is 'on' by default.
'print-completions-horizontally'
If set to 'on', Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down
the screen. The default is 'off'.
'revert-all-at-newline'
If set to 'on', Readline will undo all changes to history
lines before returning when 'accept-line' is executed. By
default, history lines may be modified and retain individual
undo lists across calls to 'readline'. The default is 'off'.
'show-all-if-ambiguous'
This alters the default behavior of the completion functions.
If set to 'on', words which have more than one possible
completion cause the matches to be listed immediately instead
of ringing the bell. The default value is 'off'.
'show-all-if-unmodified'
This alters the default behavior of the completion functions
in a fashion similar to SHOW-ALL-IF-AMBIGUOUS. If set to
'on', words which have more than one possible completion
without any possible partial completion (the possible
completions don't share a common prefix) cause the matches to
be listed immediately instead of ringing the bell. The
default value is 'off'.
'show-mode-in-prompt'
If set to 'on', add a string to the beginning of the prompt
indicating the editing mode: emacs, vi command, or vi
insertion. The mode strings are user-settable (e.g.,
EMACS-MODE-STRING). The default value is 'off'.
'skip-completed-text'
If set to 'on', this alters the default completion behavior
when inserting a single match into the line. It's only active
when performing completion in the middle of a word. If
enabled, readline does not insert characters from the
completion that match characters after point in the word being
completed, so portions of the word following the cursor are
not duplicated. For instance, if this is enabled, attempting
completion when the cursor is after the 'e' in 'Makefile' will
result in 'Makefile' rather than 'Makefilefile', assuming
there is a single possible completion. The default value is
'off'.
'vi-cmd-mode-string'
If the SHOW-MODE-IN-PROMPT variable is enabled, this string is
displayed immediately before the last line of the primary
prompt when vi editing mode is active and in command mode.
The value is expanded like a key binding, so the standard set
of meta- and control prefixes and backslash escape sequences
is available. Use the '\1' and '\2' escapes to begin and end
sequences of non-printing characters, which can be used to
embed a terminal control sequence into the mode string. The
default is '(cmd)'.
'vi-ins-mode-string'
If the SHOW-MODE-IN-PROMPT variable is enabled, this string is
displayed immediately before the last line of the primary
prompt when vi editing mode is active and in insertion mode.
The value is expanded like a key binding, so the standard set
of meta- and control prefixes and backslash escape sequences
is available. Use the '\1' and '\2' escapes to begin and end
sequences of non-printing characters, which can be used to
embed a terminal control sequence into the mode string. The
default is '(ins)'.
'visible-stats'
If set to 'on', a character denoting a file's type is appended
to the filename when listing possible completions. The
default is 'off'.
Key Bindings
The syntax for controlling key bindings in the init file is simple.
First you need to find the name of the command that you want to
change. The following sections contain tables of the command name,
the default keybinding, if any, and a short description of what the
command does.
Once you know the name of the command, simply place on a line in
the init file the name of the key you wish to bind the command to,
a colon, and then the name of the command. There can be no space
between the key name and the colon - that will be interpreted as
part of the key name. The name of the key can be expressed in
different ways, depending on what you find most comfortable.
In addition to command names, readline allows keys to be bound to a
string that is inserted when the key is pressed (a MACRO).
KEYNAME: FUNCTION-NAME or MACRO
KEYNAME is the name of a key spelled out in English. For
example:
Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: "> output"
In the example above, 'C-u' is bound to the function
'universal-argument', 'M-DEL' is bound to the function
'backward-kill-word', and 'C-o' is bound to run the macro
expressed on the right hand side (that is, to insert the text
'> output' into the line).
A number of symbolic character names are recognized while
processing this key binding syntax: DEL, ESC, ESCAPE, LFD,
NEWLINE, RET, RETURN, RUBOUT, SPACE, SPC, and TAB.
"KEYSEQ": FUNCTION-NAME or MACRO
KEYSEQ differs from KEYNAME above in that strings denoting an
entire key sequence can be specified, by placing the key
sequence in double quotes. Some GNU Emacs style key escapes
can be used, as in the following example, but the special
character names are not recognized.
"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
In the above example, 'C-u' is again bound to the function
'universal-argument' (just as it was in the first example),
''C-x' 'C-r'' is bound to the function 're-read-init-file',
and '<ESC> <[> <1> <1> <~>' is bound to insert the text
'Function Key 1'.
The following GNU Emacs style escape sequences are available when
specifying key sequences:
'\C-'
control prefix
'\M-'
meta prefix
'\e'
an escape character
'\\'
backslash
'\"'
<">, a double quotation mark
'\''
<'>, a single quote or apostrophe
In addition to the GNU Emacs style escape sequences, a second set
of backslash escapes is available:
'\a'
alert (bell)
'\b'
backspace
'\d'
delete
'\f'
form feed
'\n'
newline
'\r'
carriage return
'\t'
horizontal tab
'\v'
vertical tab
'\NNN'
the eight-bit character whose value is the octal value NNN
(one to three digits)
'\xHH'
the eight-bit character whose value is the hexadecimal value
HH (one or two hex digits)
When entering the text of a macro, single or double quotes must be
used to indicate a macro definition. Unquoted text is assumed to
be a function name. In the macro body, the backslash escapes
described above are expanded. Backslash will quote any other
character in the macro text, including '"' and '''. For example,
the following binding will make ''C-x' \' insert a single '\' into
the line:
"\C-x\\": "\\"

File: gdb.info, Node: Conditional Init Constructs, Next: Sample Init File, Prev: Readline Init File Syntax, Up: Readline Init File
32.3.2 Conditional Init Constructs
----------------------------------
Readline implements a facility similar in spirit to the conditional
compilation features of the C preprocessor which allows key bindings and
variable settings to be performed as the result of tests. There are
four parser directives used.
'$if'
The '$if' construct allows bindings to be made based on the editing
mode, the terminal being used, or the application using Readline.
The text of the test, after any comparison operator, extends to the
end of the line; unless otherwise noted, no characters are required
to isolate it.
'mode'
The 'mode=' form of the '$if' directive is used to test
whether Readline is in 'emacs' or 'vi' mode. This may be used
in conjunction with the 'set keymap' command, for instance, to
set bindings in the 'emacs-standard' and 'emacs-ctlx' keymaps
only if Readline is starting out in 'emacs' mode.
'term'
The 'term=' form may be used to include terminal-specific key
bindings, perhaps to bind the key sequences output by the
terminal's function keys. The word on the right side of the
'=' is tested against both the full name of the terminal and
the portion of the terminal name before the first '-'. This
allows 'sun' to match both 'sun' and 'sun-cmd', for instance.
'version'
The 'version' test may be used to perform comparisons against
specific Readline versions. The 'version' expands to the
current Readline version. The set of comparison operators
includes '=' (and '=='), '!=', '<=', '>=', '<', and '>'. The
version number supplied on the right side of the operator
consists of a major version number, an optional decimal point,
and an optional minor version (e.g., '7.1'). If the minor
version is omitted, it is assumed to be '0'. The operator may
be separated from the string 'version' and from the version
number argument by whitespace. The following example sets a
variable if the Readline version being used is 7.0 or newer:
$if version >= 7.0
set show-mode-in-prompt on
$endif
'application'
The APPLICATION construct is used to include
application-specific settings. Each program using the
Readline library sets the APPLICATION NAME, and you can test
for a particular value. This could be used to bind key
sequences to functions useful for a specific program. For
instance, the following command adds a key sequence that
quotes the current or previous word in Bash:
$if Bash
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
$endif
'variable'
The VARIABLE construct provides simple equality tests for
Readline variables and values. The permitted comparison
operators are '=', '==', and '!='. The variable name must be
separated from the comparison operator by whitespace; the
operator may be separated from the value on the right hand
side by whitespace. Both string and boolean variables may be
tested. Boolean variables must be tested against the values
ON and OFF. The following example is equivalent to the
'mode=emacs' test described above:
$if editing-mode == emacs
set show-mode-in-prompt on
$endif
'$endif'
This command, as seen in the previous example, terminates an '$if'
command.
'$else'
Commands in this branch of the '$if' directive are executed if the
test fails.
'$include'
This directive takes a single filename as an argument and reads
commands and bindings from that file. For example, the following
directive reads from '/etc/inputrc':
$include /etc/inputrc

File: gdb.info, Node: Sample Init File, Prev: Conditional Init Constructs, Up: Readline Init File
32.3.3 Sample Init File
-----------------------
Here is an example of an INPUTRC file. This illustrates key binding,
variable assignment, and conditional syntax.
# This file controls the behaviour of line input editing for
# programs that use the GNU Readline library. Existing
# programs include FTP, Bash, and GDB.
#
# You can re-read the inputrc file with C-x C-r.
# Lines beginning with '#' are comments.
#
# First, include any system-wide bindings and variable
# assignments from /etc/Inputrc
$include /etc/Inputrc
#
# Set various bindings for emacs mode.
set editing-mode emacs
$if mode=emacs
Meta-Control-h: backward-kill-word Text after the function name is ignored
#
# Arrow keys in keypad mode
#
#"\M-OD": backward-char
#"\M-OC": forward-char
#"\M-OA": previous-history
#"\M-OB": next-history
#
# Arrow keys in ANSI mode
#
"\M-[D": backward-char
"\M-[C": forward-char
"\M-[A": previous-history
"\M-[B": next-history
#
# Arrow keys in 8 bit keypad mode
#
#"\M-\C-OD": backward-char
#"\M-\C-OC": forward-char
#"\M-\C-OA": previous-history
#"\M-\C-OB": next-history
#
# Arrow keys in 8 bit ANSI mode
#
#"\M-\C-[D": backward-char
#"\M-\C-[C": forward-char
#"\M-\C-[A": previous-history
#"\M-\C-[B": next-history
C-q: quoted-insert
$endif
# An old-style binding. This happens to be the default.
TAB: complete
# Macros that are convenient for shell interaction
$if Bash
# edit the path
"\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
# prepare to type a quoted word --
# insert open and close double quotes
# and move to just after the open quote
"\C-x\"": "\"\"\C-b"
# insert a backslash (testing backslash escapes
# in sequences and macros)
"\C-x\\": "\\"
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
# Add a binding to refresh the line, which is unbound
"\C-xr": redraw-current-line
# Edit variable on current line.
"\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
$endif
# use a visible bell if one is available
set bell-style visible
# don't strip characters to 7 bits when reading
set input-meta on
# allow iso-latin1 characters to be inserted rather
# than converted to prefix-meta sequences
set convert-meta off
# display characters with the eighth bit set directly
# rather than as meta-prefixed characters
set output-meta on
# if there are more than 150 possible completions for
# a word, ask the user if he wants to see all of them
set completion-query-items 150
# For FTP
$if Ftp
"\C-xg": "get \M-?"
"\C-xt": "put \M-?"
"\M-.": yank-last-arg
$endif

File: gdb.info, Node: Bindable Readline Commands, Next: Readline vi Mode, Prev: Readline Init File, Up: Command Line Editing
32.4 Bindable Readline Commands
===============================
* Menu:
* Commands For Moving:: Moving about the line.
* Commands For History:: Getting at previous lines.
* Commands For Text:: Commands for changing text.
* Commands For Killing:: Commands for killing and yanking.
* Numeric Arguments:: Specifying numeric arguments, repeat counts.
* Commands For Completion:: Getting Readline to do the typing for you.
* Keyboard Macros:: Saving and re-executing typed characters
* Miscellaneous Commands:: Other miscellaneous commands.
This section describes Readline commands that may be bound to key
sequences. Command names without an accompanying key sequence are
unbound by default.
In the following descriptions, "point" refers to the current cursor
position, and "mark" refers to a cursor position saved by the 'set-mark'
command. The text between the point and mark is referred to as the
"region".

File: gdb.info, Node: Commands For Moving, Next: Commands For History, Up: Bindable Readline Commands
32.4.1 Commands For Moving
--------------------------
'beginning-of-line (C-a)'
Move to the start of the current line.
'end-of-line (C-e)'
Move to the end of the line.
'forward-char (C-f)'
Move forward a character.
'backward-char (C-b)'
Move back a character.
'forward-word (M-f)'
Move forward to the end of the next word. Words are composed of
letters and digits.
'backward-word (M-b)'
Move back to the start of the current or previous word. Words are
composed of letters and digits.
'previous-screen-line ()'
Attempt to move point to the same physical screen column on the
previous physical screen line. This will not have the desired
effect if the current Readline line does not take up more than one
physical line or if point is not greater than the length of the
prompt plus the screen width.
'next-screen-line ()'
Attempt to move point to the same physical screen column on the
next physical screen line. This will not have the desired effect
if the current Readline line does not take up more than one
physical line or if the length of the current Readline line is not
greater than the length of the prompt plus the screen width.
'clear-screen (C-l)'
Clear the screen and redraw the current line, leaving the current
line at the top of the screen.
'redraw-current-line ()'
Refresh the current line. By default, this is unbound.

File: gdb.info, Node: Commands For History, Next: Commands For Text, Prev: Commands For Moving, Up: Bindable Readline Commands
32.4.2 Commands For Manipulating The History
--------------------------------------------
'accept-line (Newline or Return)'
Accept the line regardless of where the cursor is. If this line is
non-empty, it may be added to the history list for future recall
with 'add_history()'. If this line is a modified history line, the
history line is restored to its original state.
'previous-history (C-p)'
Move 'back' through the history list, fetching the previous
command.
'next-history (C-n)'
Move 'forward' through the history list, fetching the next command.
'beginning-of-history (M-<)'
Move to the first line in the history.
'end-of-history (M->)'
Move to the end of the input history, i.e., the line currently
being entered.
'reverse-search-history (C-r)'
Search backward starting at the current line and moving 'up'
through the history as necessary. This is an incremental search.
'forward-search-history (C-s)'
Search forward starting at the current line and moving 'down'
through the history as necessary. This is an incremental search.
'non-incremental-reverse-search-history (M-p)'
Search backward starting at the current line and moving 'up'
through the history as necessary using a non-incremental search for
a string supplied by the user. The search string may match
anywhere in a history line.
'non-incremental-forward-search-history (M-n)'
Search forward starting at the current line and moving 'down'
through the history as necessary using a non-incremental search for
a string supplied by the user. The search string may match
anywhere in a history line.
'history-search-forward ()'
Search forward through the history for the string of characters
between the start of the current line and the point. The search
string must match at the beginning of a history line. This is a
non-incremental search. By default, this command is unbound.
'history-search-backward ()'
Search backward through the history for the string of characters
between the start of the current line and the point. The search
string must match at the beginning of a history line. This is a
non-incremental search. By default, this command is unbound.
'history-substring-search-forward ()'
Search forward through the history for the string of characters
between the start of the current line and the point. The search
string may match anywhere in a history line. This is a
non-incremental search. By default, this command is unbound.
'history-substring-search-backward ()'
Search backward through the history for the string of characters
between the start of the current line and the point. The search
string may match anywhere in a history line. This is a
non-incremental search. By default, this command is unbound.
'yank-nth-arg (M-C-y)'
Insert the first argument to the previous command (usually the
second word on the previous line) at point. With an argument N,
insert the Nth word from the previous command (the words in the
previous command begin with word 0). A negative argument inserts
the Nth word from the end of the previous command. Once the
argument N is computed, the argument is extracted as if the '!N'
history expansion had been specified.
'yank-last-arg (M-. or M-_)'
Insert last argument to the previous command (the last word of the
previous history entry). With a numeric argument, behave exactly
like 'yank-nth-arg'. Successive calls to 'yank-last-arg' move back
through the history list, inserting the last word (or the word
specified by the argument to the first call) of each line in turn.
Any numeric argument supplied to these successive calls determines
the direction to move through the history. A negative argument
switches the direction through the history (back or forward). The
history expansion facilities are used to extract the last argument,
as if the '!$' history expansion had been specified.

File: gdb.info, Node: Commands For Text, Next: Commands For Killing, Prev: Commands For History, Up: Bindable Readline Commands
32.4.3 Commands For Changing Text
---------------------------------
'end-of-file (usually C-d)'
The character indicating end-of-file as set, for example, by
'stty'. If this character is read when there are no characters on
the line, and point is at the beginning of the line, Readline
interprets it as the end of input and returns EOF.
'delete-char (C-d)'
Delete the character at point. If this function is bound to the
same character as the tty EOF character, as 'C-d' commonly is, see
above for the effects.
'backward-delete-char (Rubout)'
Delete the character behind the cursor. A numeric argument means
to kill the characters instead of deleting them.
'forward-backward-delete-char ()'
Delete the character under the cursor, unless the cursor is at the
end of the line, in which case the character behind the cursor is
deleted. By default, this is not bound to a key.
'quoted-insert (C-q or C-v)'
Add the next character typed to the line verbatim. This is how to
insert key sequences like 'C-q', for example.
'tab-insert (M-<TAB>)'
Insert a tab character.
'self-insert (a, b, A, 1, !, ...)'
Insert yourself.
'bracketed-paste-begin ()'
This function is intended to be bound to the "bracketed paste"
escape sequence sent by some terminals, and such a binding is
assigned by default. It allows Readline to insert the pasted text
as a single unit without treating each character as if it had been
read from the keyboard. The characters are inserted as if each one
was bound to 'self-insert' instead of executing any editing
commands.
'transpose-chars (C-t)'
Drag the character before the cursor forward over the character at
the cursor, moving the cursor forward as well. If the insertion
point is at the end of the line, then this transposes the last two
characters of the line. Negative arguments have no effect.
'transpose-words (M-t)'
Drag the word before point past the word after point, moving point
past that word as well. If the insertion point is at the end of
the line, this transposes the last two words on the line.
'upcase-word (M-u)'
Uppercase the current (or following) word. With a negative
argument, uppercase the previous word, but do not move the cursor.
'downcase-word (M-l)'
Lowercase the current (or following) word. With a negative
argument, lowercase the previous word, but do not move the cursor.
'capitalize-word (M-c)'
Capitalize the current (or following) word. With a negative
argument, capitalize the previous word, but do not move the cursor.
'overwrite-mode ()'
Toggle overwrite mode. With an explicit positive numeric argument,
switches to overwrite mode. With an explicit non-positive numeric
argument, switches to insert mode. This command affects only
'emacs' mode; 'vi' mode does overwrite differently. Each call to
'readline()' starts in insert mode.
In overwrite mode, characters bound to 'self-insert' replace the
text at point rather than pushing the text to the right.
Characters bound to 'backward-delete-char' replace the character
before point with a space.
By default, this command is unbound.

File: gdb.info, Node: Commands For Killing, Next: Numeric Arguments, Prev: Commands For Text, Up: Bindable Readline Commands
32.4.4 Killing And Yanking
--------------------------
'kill-line (C-k)'
Kill the text from point to the end of the line.
'backward-kill-line (C-x Rubout)'
Kill backward from the cursor to the beginning of the current line.
'unix-line-discard (C-u)'
Kill backward from the cursor to the beginning of the current line.
'kill-whole-line ()'
Kill all characters on the current line, no matter where point is.
By default, this is unbound.
'kill-word (M-d)'
Kill from point to the end of the current word, or if between
words, to the end of the next word. Word boundaries are the same
as 'forward-word'.
'backward-kill-word (M-<DEL>)'
Kill the word behind point. Word boundaries are the same as
'backward-word'.
'unix-word-rubout (C-w)'
Kill the word behind point, using white space as a word boundary.
The killed text is saved on the kill-ring.
'unix-filename-rubout ()'
Kill the word behind point, using white space and the slash
character as the word boundaries. The killed text is saved on the
kill-ring.
'delete-horizontal-space ()'
Delete all spaces and tabs around point. By default, this is
unbound.
'kill-region ()'
Kill the text in the current region. By default, this command is
unbound.
'copy-region-as-kill ()'
Copy the text in the region to the kill buffer, so it can be yanked
right away. By default, this command is unbound.
'copy-backward-word ()'
Copy the word before point to the kill buffer. The word boundaries
are the same as 'backward-word'. By default, this command is
unbound.
'copy-forward-word ()'
Copy the word following point to the kill buffer. The word
boundaries are the same as 'forward-word'. By default, this
command is unbound.
'yank (C-y)'
Yank the top of the kill ring into the buffer at point.
'yank-pop (M-y)'
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is 'yank' or 'yank-pop'.

File: gdb.info, Node: Numeric Arguments, Next: Commands For Completion, Prev: Commands For Killing, Up: Bindable Readline Commands
32.4.5 Specifying Numeric Arguments
-----------------------------------
'digit-argument (M-0, M-1, ... M--)'
Add this digit to the argument already accumulating, or start a new
argument. 'M--' starts a negative argument.
'universal-argument ()'
This is another way to specify an argument. If this command is
followed by one or more digits, optionally with a leading minus
sign, those digits define the argument. If the command is followed
by digits, executing 'universal-argument' again ends the numeric
argument, but is otherwise ignored. As a special case, if this
command is immediately followed by a character that is neither a
digit nor minus sign, the argument count for the next command is
multiplied by four. The argument count is initially one, so
executing this function the first time makes the argument count
four, a second time makes the argument count sixteen, and so on.
By default, this is not bound to a key.

File: gdb.info, Node: Commands For Completion, Next: Keyboard Macros, Prev: Numeric Arguments, Up: Bindable Readline Commands
32.4.6 Letting Readline Type For You
------------------------------------
'complete (<TAB>)'
Attempt to perform completion on the text before point. The actual
completion performed is application-specific. The default is
filename completion.
'possible-completions (M-?)'
List the possible completions of the text before point. When
displaying completions, Readline sets the number of columns used
for display to the value of 'completion-display-width', the value
of the environment variable 'COLUMNS', or the screen width, in that
order.
'insert-completions (M-*)'
Insert all completions of the text before point that would have
been generated by 'possible-completions'.
'menu-complete ()'
Similar to 'complete', but replaces the word to be completed with a
single match from the list of possible completions. Repeated
execution of 'menu-complete' steps through the list of possible
completions, inserting each match in turn. At the end of the list
of completions, the bell is rung (subject to the setting of
'bell-style') and the original text is restored. An argument of N
moves N positions forward in the list of matches; a negative
argument may be used to move backward through the list. This
command is intended to be bound to <TAB>, but is unbound by
default.
'menu-complete-backward ()'
Identical to 'menu-complete', but moves backward through the list
of possible completions, as if 'menu-complete' had been given a
negative argument.
'delete-char-or-list ()'
Deletes the character under the cursor if not at the beginning or
end of the line (like 'delete-char'). If at the end of the line,
behaves identically to 'possible-completions'. This command is
unbound by default.

File: gdb.info, Node: Keyboard Macros, Next: Miscellaneous Commands, Prev: Commands For Completion, Up: Bindable Readline Commands
32.4.7 Keyboard Macros
----------------------
'start-kbd-macro (C-x ()'
Begin saving the characters typed into the current keyboard macro.
'end-kbd-macro (C-x ))'
Stop saving the characters typed into the current keyboard macro
and save the definition.
'call-last-kbd-macro (C-x e)'
Re-execute the last keyboard macro defined, by making the
characters in the macro appear as if typed at the keyboard.
'print-last-kbd-macro ()'
Print the last keboard macro defined in a format suitable for the
INPUTRC file.

File: gdb.info, Node: Miscellaneous Commands, Prev: Keyboard Macros, Up: Bindable Readline Commands
32.4.8 Some Miscellaneous Commands
----------------------------------
're-read-init-file (C-x C-r)'
Read in the contents of the INPUTRC file, and incorporate any
bindings or variable assignments found there.
'abort (C-g)'
Abort the current editing command and ring the terminal's bell
(subject to the setting of 'bell-style').
'do-lowercase-version (M-A, M-B, M-X, ...)'
If the metafied character X is upper case, run the command that is
bound to the corresponding metafied lower case character. The
behavior is undefined if X is already lower case.
'prefix-meta (<ESC>)'
Metafy the next character typed. This is for keyboards without a
meta key. Typing '<ESC> f' is equivalent to typing 'M-f'.
'undo (C-_ or C-x C-u)'
Incremental undo, separately remembered for each line.
'revert-line (M-r)'
Undo all changes made to this line. This is like executing the
'undo' command enough times to get back to the beginning.
'tilde-expand (M-~)'
Perform tilde expansion on the current word.
'set-mark (C-@)'
Set the mark to the point. If a numeric argument is supplied, the
mark is set to that position.
'exchange-point-and-mark (C-x C-x)'
Swap the point with the mark. The current cursor position is set
to the saved position, and the old cursor position is saved as the
mark.
'character-search (C-])'
A character is read and point is moved to the next occurrence of
that character. A negative count searches for previous
occurrences.
'character-search-backward (M-C-])'
A character is read and point is moved to the previous occurrence
of that character. A negative count searches for subsequent
occurrences.
'skip-csi-sequence ()'
Read enough characters to consume a multi-key sequence such as
those defined for keys like Home and End. Such sequences begin
with a Control Sequence Indicator (CSI), usually ESC-[. If this
sequence is bound to "\e[", keys producing such sequences will have
no effect unless explicitly bound to a readline command, instead of
inserting stray characters into the editing buffer. This is
unbound by default, but usually bound to ESC-[.
'insert-comment (M-#)'
Without a numeric argument, the value of the 'comment-begin'
variable is inserted at the beginning of the current line. If a
numeric argument is supplied, this command acts as a toggle: if the
characters at the beginning of the line do not match the value of
'comment-begin', the value is inserted, otherwise the characters in
'comment-begin' are deleted from the beginning of the line. In
either case, the line is accepted as if a newline had been typed.
'dump-functions ()'
Print all of the functions and their key bindings to the Readline
output stream. If a numeric argument is supplied, the output is
formatted in such a way that it can be made part of an INPUTRC
file. This command is unbound by default.
'dump-variables ()'
Print all of the settable variables and their values to the
Readline output stream. If a numeric argument is supplied, the
output is formatted in such a way that it can be made part of an
INPUTRC file. This command is unbound by default.
'dump-macros ()'
Print all of the Readline key sequences bound to macros and the
strings they output. If a numeric argument is supplied, the output
is formatted in such a way that it can be made part of an INPUTRC
file. This command is unbound by default.
'emacs-editing-mode (C-e)'
When in 'vi' command mode, this causes a switch to 'emacs' editing
mode.
'vi-editing-mode (M-C-j)'
When in 'emacs' editing mode, this causes a switch to 'vi' editing
mode.

File: gdb.info, Node: Readline vi Mode, Prev: Bindable Readline Commands, Up: Command Line Editing
32.5 Readline vi Mode
=====================
While the Readline library does not have a full set of 'vi' editing
functions, it does contain enough to allow simple editing of the line.
The Readline 'vi' mode behaves as specified in the POSIX standard.
In order to switch interactively between 'emacs' and 'vi' editing
modes, use the command 'M-C-j' (bound to emacs-editing-mode when in 'vi'
mode and to vi-editing-mode in 'emacs' mode). The Readline default is
'emacs' mode.
When you enter a line in 'vi' mode, you are already placed in
'insertion' mode, as if you had typed an 'i'. Pressing <ESC> switches
you into 'command' mode, where you can edit the text of the line with
the standard 'vi' movement keys, move to previous history lines with 'k'
and subsequent lines with 'j', and so forth.

File: gdb.info, Node: Using History Interactively, Next: In Memoriam, Prev: Command Line Editing, Up: Top
33 Using History Interactively
******************************
This chapter describes how to use the GNU History Library interactively,
from a user's standpoint. It should be considered a user's guide. For
information on using the GNU History Library in your own programs, *note
(history)Programming with GNU History::.
* Menu:
* History Interaction:: What it feels like using History as a user.

File: gdb.info, Node: History Interaction, Up: Using History Interactively
33.1 History Expansion
======================
The History library provides a history expansion feature that is similar
to the history expansion provided by 'csh'. This section describes the
syntax used to manipulate the history information.
History expansions introduce words from the history list into the
input stream, making it easy to repeat commands, insert the arguments to
a previous command into the current input line, or fix errors in
previous commands quickly.
History expansion takes place in two parts. The first is to
determine which line from the history list should be used during
substitution. The second is to select portions of that line for
inclusion into the current one. The line selected from the history is
called the "event", and the portions of that line that are acted upon
are called "words". Various "modifiers" are available to manipulate the
selected words. The line is broken into words in the same fashion that
Bash does, so that several words surrounded by quotes are considered one
word. History expansions are introduced by the appearance of the
history expansion character, which is '!' by default.
History expansion implements shell-like quoting conventions: a
backslash can be used to remove the special handling for the next
character; single quotes enclose verbatim sequences of characters, and
can be used to inhibit history expansion; and characters enclosed within
double quotes may be subject to history expansion, since backslash can
escape the history expansion character, but single quotes may not, since
they are not treated specially within double quotes.
* Menu:
* Event Designators:: How to specify which history line to use.
* Word Designators:: Specifying which words are of interest.
* Modifiers:: Modifying the results of substitution.

File: gdb.info, Node: Event Designators, Next: Word Designators, Up: History Interaction
33.1.1 Event Designators
------------------------
An event designator is a reference to a command line entry in the
history list. Unless the reference is absolute, events are relative to
the current position in the history list.
'!'
Start a history substitution, except when followed by a space, tab,
the end of the line, or '='.
'!N'
Refer to command line N.
'!-N'
Refer to the command N lines back.
'!!'
Refer to the previous command. This is a synonym for '!-1'.
'!STRING'
Refer to the most recent command preceding the current position in
the history list starting with STRING.
'!?STRING[?]'
Refer to the most recent command preceding the current position in
the history list containing STRING. The trailing '?' may be
omitted if the STRING is followed immediately by a newline.
'^STRING1^STRING2^'
Quick Substitution. Repeat the last command, replacing STRING1
with STRING2. Equivalent to '!!:s/STRING1/STRING2/'.
'!#'
The entire command line typed so far.

File: gdb.info, Node: Word Designators, Next: Modifiers, Prev: Event Designators, Up: History Interaction
33.1.2 Word Designators
-----------------------
Word designators are used to select desired words from the event. A ':'
separates the event specification from the word designator. It may be
omitted if the word designator begins with a '^', '$', '*', '-', or '%'.
Words are numbered from the beginning of the line, with the first word
being denoted by 0 (zero). Words are inserted into the current line
separated by single spaces.
For example,
'!!'
designates the preceding command. When you type this, the
preceding command is repeated in toto.
'!!:$'
designates the last argument of the preceding command. This may be
shortened to '!$'.
'!fi:2'
designates the second argument of the most recent command starting
with the letters 'fi'.
Here are the word designators:
'0 (zero)'
The '0'th word. For many applications, this is the command word.
'N'
The Nth word.
'^'
The first argument; that is, word 1.
'$'
The last argument.
'%'
The word matched by the most recent '?STRING?' search.
'X-Y'
A range of words; '-Y' abbreviates '0-Y'.
'*'
All of the words, except the '0'th. This is a synonym for '1-$'.
It is not an error to use '*' if there is just one word in the
event; the empty string is returned in that case.
'X*'
Abbreviates 'X-$'
'X-'
Abbreviates 'X-$' like 'X*', but omits the last word.
If a word designator is supplied without an event specification, the
previous command is used as the event.

File: gdb.info, Node: Modifiers, Prev: Word Designators, Up: History Interaction
33.1.3 Modifiers
----------------
After the optional word designator, you can add a sequence of one or
more of the following modifiers, each preceded by a ':'.
'h'
Remove a trailing pathname component, leaving only the head.
't'
Remove all leading pathname components, leaving the tail.
'r'
Remove a trailing suffix of the form '.SUFFIX', leaving the
basename.
'e'
Remove all but the trailing suffix.
'p'
Print the new command but do not execute it.
's/OLD/NEW/'
Substitute NEW for the first occurrence of OLD in the event line.
Any delimiter may be used in place of '/'. The delimiter may be
quoted in OLD and NEW with a single backslash. If '&' appears in
NEW, it is replaced by OLD. A single backslash will quote the '&'.
The final delimiter is optional if it is the last character on the
input line.
'&'
Repeat the previous substitution.
'g'
'a'
Cause changes to be applied over the entire event line. Used in
conjunction with 's', as in 'gs/OLD/NEW/', or with '&'.
'G'
Apply the following 's' modifier once to each word in the event.

File: gdb.info, Node: In Memoriam, Next: Formatting Documentation, Prev: Using History Interactively, Up: Top
Appendix A In Memoriam
**********************
The GDB project mourns the loss of the following long-time contributors:
'Fred Fish'
Fred was a long-standing contributor to GDB (1991-2006), and to
Free Software in general. Outside of GDB, he was known in the
Amiga world for his series of Fish Disks, and the GeekGadget
project.
'Michael Snyder'
Michael was one of the Global Maintainers of the GDB project, with
contributions recorded as early as 1996, until 2011. In addition
to his day to day participation, he was a large driving force
behind adding Reverse Debugging to GDB.
Beyond their technical contributions to the project, they were also
enjoyable members of the Free Software Community. We will miss them.

File: gdb.info, Node: Formatting Documentation, Next: Installing GDB, Prev: In Memoriam, Up: Top
Appendix B Formatting Documentation
***********************************
The GDB 4 release includes an already-formatted reference card, ready
for printing with PostScript or Ghostscript, in the 'gdb' subdirectory
of the main source directory(1). If you can use PostScript or
Ghostscript with your printer, you can print the reference card
immediately with 'refcard.ps'.
The release also includes the source for the reference card. You can
format it, using TeX, by typing:
make refcard.dvi
The GDB reference card is designed to print in "landscape" mode on US
"letter" size paper; that is, on a sheet 11 inches wide by 8.5 inches
high. You will need to specify this form of printing as an option to
your DVI output program.
All the documentation for GDB comes as part of the machine-readable
distribution. The documentation is written in Texinfo format, which is
a documentation system that uses a single source file to produce both
on-line information and a printed manual. You can use one of the Info
formatting commands to create the on-line version of the documentation
and TeX (or 'texi2roff') to typeset the printed version.
GDB includes an already formatted copy of the on-line Info version of
this manual in the 'gdb' subdirectory. The main Info file is
'gdb-9.2/gdb/gdb.info', and it refers to subordinate files matching
'gdb.info*' in the same directory. If necessary, you can print out
these files, or read them with any editor; but they are easier to read
using the 'info' subsystem in GNU Emacs or the standalone 'info'
program, available as part of the GNU Texinfo distribution.
If you want to format these Info files yourself, you need one of the
Info formatting programs, such as 'texinfo-format-buffer' or 'makeinfo'.
If you have 'makeinfo' installed, and are in the top level GDB source
directory ('gdb-9.2', in the case of version 9.2), you can make the Info
file by typing:
cd gdb
make gdb.info
If you want to typeset and print copies of this manual, you need TeX,
a program to print its DVI output files, and 'texinfo.tex', the Texinfo
definitions file.
TeX is a typesetting program; it does not print files directly, but
produces output files called DVI files. To print a typeset document,
you need a program to print DVI files. If your system has TeX
installed, chances are it has such a program. The precise command to
use depends on your system; 'lpr -d' is common; another (for PostScript
devices) is 'dvips'. The DVI print command may require a file name
without any extension or a '.dvi' extension.
TeX also requires a macro definitions file called 'texinfo.tex'.
This file tells TeX how to typeset a document written in Texinfo format.
On its own, TeX cannot either read or typeset a Texinfo file.
'texinfo.tex' is distributed with GDB and is located in the
'gdb-VERSION-NUMBER/texinfo' directory.
If you have TeX and a DVI printer program installed, you can typeset
and print this manual. First switch to the 'gdb' subdirectory of the
main source directory (for example, to 'gdb-9.2/gdb') and type:
make gdb.dvi
Then give 'gdb.dvi' to your DVI printing program.
---------- Footnotes ----------
(1) In 'gdb-9.2/gdb/refcard.ps' of the version 9.2 release.

File: gdb.info, Node: Installing GDB, Next: Maintenance Commands, Prev: Formatting Documentation, Up: Top
Appendix C Installing GDB
*************************
* Menu:
* Requirements:: Requirements for building GDB
* Running Configure:: Invoking the GDB 'configure' script
* Separate Objdir:: Compiling GDB in another directory
* Config Names:: Specifying names for hosts and targets
* Configure Options:: Summary of options for configure
* System-wide configuration:: Having a system-wide init file

File: gdb.info, Node: Requirements, Next: Running Configure, Up: Installing GDB
C.1 Requirements for Building GDB
=================================
Building GDB requires various tools and packages to be available. Other
packages will be used only if they are found.
Tools/Packages Necessary for Building GDB
=========================================
C++11 compiler
GDB is written in C++11. It should be buildable with any recent
C++11 compiler, e.g. GCC.
GNU make
GDB's build system relies on features only found in the GNU make
program. Other variants of 'make' will not work.
Tools/Packages Optional for Building GDB
========================================
Expat
GDB can use the Expat XML parsing library. This library may be
included with your operating system distribution; if it is not, you
can get the latest version from <http://expat.sourceforge.net>.
The 'configure' script will search for this library in several
standard locations; if it is installed in an unusual path, you can
use the '--with-libexpat-prefix' option to specify its location.
Expat is used for:
* Remote protocol memory maps (*note Memory Map Format::)
* Target descriptions (*note Target Descriptions::)
* Remote shared library lists (*Note Library List Format::, or
alternatively *note Library List Format for SVR4 Targets::)
* MS-Windows shared libraries (*note Shared Libraries::)
* Traceframe info (*note Traceframe Info Format::)
* Branch trace (*note Branch Trace Format::, *note Branch Trace
Configuration Format::)
Guile
GDB can be scripted using GNU Guile. *Note Guile::. By default,
GDB will be compiled if the Guile libraries are installed and are
found by 'configure'. You can use the '--with-guile' option to
request Guile, and pass either the Guile version number or the file
name of the relevant 'pkg-config' program to choose a particular
version of Guile.
iconv
GDB's features related to character sets (*note Character Sets::)
require a functioning 'iconv' implementation. If you are on a GNU
system, then this is provided by the GNU C Library. Some other
systems also provide a working 'iconv'.
If GDB is using the 'iconv' program which is installed in a
non-standard place, you will need to tell GDB where to find it.
This is done with '--with-iconv-bin' which specifies the directory
that contains the 'iconv' program. This program is run in order to
make a list of the available character sets.
On systems without 'iconv', you can install GNU Libiconv. If
Libiconv is installed in a standard place, GDB will automatically
use it if it is needed. If you have previously installed Libiconv
in a non-standard place, you can use the '--with-libiconv-prefix'
option to 'configure'.
GDB's top-level 'configure' and 'Makefile' will arrange to build
Libiconv if a directory named 'libiconv' appears in the top-most
source directory. If Libiconv is built this way, and if the
operating system does not provide a suitable 'iconv'
implementation, then the just-built library will automatically be
used by GDB. One easy way to set this up is to download GNU
Libiconv, unpack it inside the top-level directory of the GDB
source tree, and then rename the directory holding the Libiconv
source code to 'libiconv'.
lzma
GDB can support debugging sections that are compressed with the
LZMA library. *Note MiniDebugInfo::. If this library is not
included with your operating system, you can find it in the xz
package at <http://tukaani.org/xz/>. If the LZMA library is
available in the usual place, then the 'configure' script will use
it automatically. If it is installed in an unusual path, you can
use the '--with-lzma-prefix' option to specify its location.
MPFR
GDB can use the GNU MPFR multiple-precision floating-point library.
This library may be included with your operating system
distribution; if it is not, you can get the latest version from
<http://www.mpfr.org>. The 'configure' script will search for this
library in several standard locations; if it is installed in an
unusual path, you can use the '--with-libmpfr-prefix' option to
specify its location.
GNU MPFR is used to emulate target floating-point arithmetic during
expression evaluation when the target uses different floating-point
formats than the host. If GNU MPFR it is not available, GDB will
fall back to using host floating-point arithmetic.
Python
GDB can be scripted using Python language. *Note Python::. By
default, GDB will be compiled if the Python libraries are installed
and are found by 'configure'. You can use the '--with-python'
option to request Python, and pass either the file name of the
relevant 'python' executable, or the name of the directory in which
Python is installed, to choose a particular installation of Python.
zlib
GDB will use the 'zlib' library, if available, to read compressed
debug sections. Some linkers, such as GNU gold, are capable of
producing binaries with compressed debug sections. If GDB is
compiled with 'zlib', it will be able to read the debug information
in such binaries.
The 'zlib' library is likely included with your operating system
distribution; if it is not, you can get the latest version from
<http://zlib.net>.

File: gdb.info, Node: Running Configure, Next: Separate Objdir, Prev: Requirements, Up: Installing GDB
C.2 Invoking the GDB 'configure' Script
=======================================
GDB comes with a 'configure' script that automates the process of
preparing GDB for installation; you can then use 'make' to build the
'gdb' program.
The GDB distribution includes all the source code you need for GDB in
a single directory, whose name is usually composed by appending the
version number to 'gdb'.
For example, the GDB version 9.2 distribution is in the 'gdb-9.2'
directory. That directory contains:
'gdb-9.2/configure (and supporting files)'
script for configuring GDB and all its supporting libraries
'gdb-9.2/gdb'
the source specific to GDB itself
'gdb-9.2/bfd'
source for the Binary File Descriptor library
'gdb-9.2/include'
GNU include files
'gdb-9.2/libiberty'
source for the '-liberty' free software library
'gdb-9.2/opcodes'
source for the library of opcode tables and disassemblers
'gdb-9.2/readline'
source for the GNU command-line interface
There may be other subdirectories as well.
The simplest way to configure and build GDB is to run 'configure'
from the 'gdb-VERSION-NUMBER' source directory, which in this example is
the 'gdb-9.2' directory.
First switch to the 'gdb-VERSION-NUMBER' source directory if you are
not already in it; then run 'configure'. Pass the identifier for the
platform on which GDB will run as an argument.
For example:
cd gdb-9.2
./configure
make
Running 'configure' and then running 'make' builds the included
supporting libraries, then 'gdb' itself. The configured source files,
and the binaries, are left in the corresponding source directories.
'configure' is a Bourne-shell ('/bin/sh') script; if your system does
not recognize this automatically when you run a different shell, you may
need to run 'sh' on it explicitly:
sh configure
You should run the 'configure' script from the top directory in the
source tree, the 'gdb-VERSION-NUMBER' directory. If you run 'configure'
from one of the subdirectories, you will configure only that
subdirectory. That is usually not what you want. In particular, if you
run the first 'configure' from the 'gdb' subdirectory of the
'gdb-VERSION-NUMBER' directory, you will omit the configuration of
'bfd', 'readline', and other sibling directories of the 'gdb'
subdirectory. This leads to build errors about missing include files
such as 'bfd/bfd.h'.
You can install 'GDB' anywhere. The best way to do this is to pass
the '--prefix' option to 'configure', and then install it with 'make
install'.

File: gdb.info, Node: Separate Objdir, Next: Config Names, Prev: Running Configure, Up: Installing GDB
C.3 Compiling GDB in Another Directory
======================================
If you want to run GDB versions for several host or target machines, you
need a different 'gdb' compiled for each combination of host and target.
'configure' is designed to make this easy by allowing you to generate
each configuration in a separate subdirectory, rather than in the source
directory. If your 'make' program handles the 'VPATH' feature (GNU
'make' does), running 'make' in each of these directories builds the
'gdb' program specified there.
To build 'gdb' in a separate directory, run 'configure' with the
'--srcdir' option to specify where to find the source. (You also need
to specify a path to find 'configure' itself from your working
directory. If the path to 'configure' would be the same as the argument
to '--srcdir', you can leave out the '--srcdir' option; it is assumed.)
For example, with version 9.2, you can build GDB in a separate
directory for a Sun 4 like this:
cd gdb-9.2
mkdir ../gdb-sun4
cd ../gdb-sun4
../gdb-9.2/configure
make
When 'configure' builds a configuration using a remote source
directory, it creates a tree for the binaries with the same structure
(and using the same names) as the tree under the source directory. In
the example, you'd find the Sun 4 library 'libiberty.a' in the directory
'gdb-sun4/libiberty', and GDB itself in 'gdb-sun4/gdb'.
Make sure that your path to the 'configure' script has just one
instance of 'gdb' in it. If your path to 'configure' looks like
'../gdb-9.2/gdb/configure', you are configuring only one subdirectory of
GDB, not the whole package. This leads to build errors about missing
include files such as 'bfd/bfd.h'.
One popular reason to build several GDB configurations in separate
directories is to configure GDB for cross-compiling (where GDB runs on
one machine--the "host"--while debugging programs that run on another
machine--the "target"). You specify a cross-debugging target by giving
the '--target=TARGET' option to 'configure'.
When you run 'make' to build a program or library, you must run it in
a configured directory--whatever directory you were in when you called
'configure' (or one of its subdirectories).
The 'Makefile' that 'configure' generates in each source directory
also runs recursively. If you type 'make' in a source directory such as
'gdb-9.2' (or in a separate configured directory configured with
'--srcdir=DIRNAME/gdb-9.2'), you will build all the required libraries,
and then build GDB.
When you have multiple hosts or targets configured in separate
directories, you can run 'make' on them in parallel (for example, if
they are NFS-mounted on each of the hosts); they will not interfere with
each other.

File: gdb.info, Node: Config Names, Next: Configure Options, Prev: Separate Objdir, Up: Installing GDB
C.4 Specifying Names for Hosts and Targets
==========================================
The specifications used for hosts and targets in the 'configure' script
are based on a three-part naming scheme, but some short predefined
aliases are also supported. The full naming scheme encodes three pieces
of information in the following pattern:
ARCHITECTURE-VENDOR-OS
For example, you can use the alias 'sun4' as a HOST argument, or as
the value for TARGET in a '--target=TARGET' option. The equivalent full
name is 'sparc-sun-sunos4'.
The 'configure' script accompanying GDB does not provide any query
facility to list all supported host and target names or aliases.
'configure' calls the Bourne shell script 'config.sub' to map
abbreviations to full names; you can read the script, if you wish, or
you can use it to test your guesses on abbreviations--for example:
% sh config.sub i386-linux
i386-pc-linux-gnu
% sh config.sub alpha-linux
alpha-unknown-linux-gnu
% sh config.sub hp9k700
hppa1.1-hp-hpux
% sh config.sub sun4
sparc-sun-sunos4.1.1
% sh config.sub sun3
m68k-sun-sunos4.1.1
% sh config.sub i986v
Invalid configuration `i986v': machine `i986v' not recognized
'config.sub' is also distributed in the GDB source directory ('gdb-9.2',
for version 9.2).

File: gdb.info, Node: Configure Options, Next: System-wide configuration, Prev: Config Names, Up: Installing GDB
C.5 'configure' Options
=======================
Here is a summary of the 'configure' options and arguments that are most
often useful for building GDB. 'configure' also has several other
options not listed here. *note (autoconf.info)Running configure
scripts::, for a full explanation of 'configure'.
configure [--help]
[--prefix=DIR]
[--exec-prefix=DIR]
[--srcdir=DIRNAME]
[--target=TARGET]
You may introduce options with a single '-' rather than '--' if you
prefer; but you may abbreviate option names if you use '--'.
'--help'
Display a quick summary of how to invoke 'configure'.
'--prefix=DIR'
Configure the source to install programs and files under directory
'DIR'.
'--exec-prefix=DIR'
Configure the source to install programs under directory 'DIR'.
'--srcdir=DIRNAME'
Use this option to make configurations in directories separate from
the GDB source directories. Among other things, you can use this
to build (or maintain) several configurations simultaneously, in
separate directories. 'configure' writes configuration-specific
files in the current directory, but arranges for them to use the
source in the directory DIRNAME. 'configure' creates directories
under the working directory in parallel to the source directories
below DIRNAME.
'--target=TARGET'
Configure GDB for cross-debugging programs running on the specified
TARGET. Without this option, GDB is configured to debug programs
that run on the same machine (HOST) as GDB itself.
There is no convenient way to generate a list of all available
targets. Also see the '--enable-targets' option, below.
There are many other options that are specific to GDB. This lists
just the most common ones; there are some very specialized options not
described here.
'--enable-targets=[TARGET]...'
'--enable-targets=all'
Configure GDB for cross-debugging programs running on the specified
list of targets. The special value 'all' configures GDB for
debugging programs running on any target it supports.
'--with-gdb-datadir=PATH'
Set the GDB-specific data directory. GDB will look here for
certain supporting files or scripts. This defaults to the 'gdb'
subdirectory of 'datadir' (which can be set using '--datadir').
'--with-relocated-sources=DIR'
Sets up the default source path substitution rule so that directory
names recorded in debug information will be automatically adjusted
for any directory under DIR. DIR should be a subdirectory of GDB's
configured prefix, the one mentioned in the '--prefix' or
'--exec-prefix' options to configure. This option is useful if GDB
is supposed to be moved to a different place after it is built.
'--enable-64-bit-bfd'
Enable 64-bit support in BFD on 32-bit hosts.
'--disable-gdbmi'
Build GDB without the GDB/MI machine interface (*note GDB/MI::).
'--enable-tui'
Build GDB with the text-mode full-screen user interface (TUI).
Requires a curses library (ncurses and cursesX are also supported).
'--with-curses'
Use the curses library instead of the termcap library, for
text-mode terminal operations.
'--with-libunwind-ia64'
Use the libunwind library for unwinding function call stack on ia64
target platforms. See http://www.nongnu.org/libunwind/index.html
for details.
'--with-system-readline'
Use the readline library installed on the host, rather than the
library supplied as part of GDB. Readline 7 or newer is required;
this is enforced by the build system.
'--with-system-zlib'
Use the zlib library installed on the host, rather than the library
supplied as part of GDB.
'--with-expat'
Build GDB with Expat, a library for XML parsing. (Done by default
if libexpat is installed and found at configure time.) This
library is used to read XML files supplied with GDB. If it is
unavailable, some features, such as remote protocol memory maps,
target descriptions, and shared library lists, that are based on
XML files, will not be available in GDB. If your host does not
have libexpat installed, you can get the latest version from
'http://expat.sourceforge.net'.
'--with-libiconv-prefix[=DIR]'
Build GDB with GNU libiconv, a character set encoding conversion
library. This is not done by default, as on GNU systems the
'iconv' that is built in to the C library is sufficient. If your
host does not have a working 'iconv', you can get the latest
version of GNU iconv from 'https://www.gnu.org/software/libiconv/'.
GDB's build system also supports building GNU libiconv as part of
the overall build. *Note Requirements::.
'--with-lzma'
Build GDB with LZMA, a compression library. (Done by default if
liblzma is installed and found at configure time.) LZMA is used by
GDB's "mini debuginfo" feature, which is only useful on platforms
using the ELF object file format. If your host does not have
liblzma installed, you can get the latest version from
'https://tukaani.org/xz/'.
'--with-mpfr'
Build GDB with GNU MPFR, a library for multiple-precision
floating-point computation with correct rounding. (Done by default
if GNU MPFR is installed and found at configure time.) This
library is used to emulate target floating-point arithmetic during
expression evaluation when the target uses different floating-point
formats than the host. If GNU MPFR is not available, GDB will fall
back to using host floating-point arithmetic. If your host does
not have GNU MPFR installed, you can get the latest version from
'http://www.mpfr.org'.
'--with-python[=PYTHON]'
Build GDB with Python scripting support. (Done by default if
libpython is present and found at configure time.) Python makes
GDB scripting much more powerful than the restricted CLI scripting
language. If your host does not have Python installed, you can
find it on 'http://www.python.org/download/'. The oldest version
of Python supported by GDB is 2.6. The optional argument PYTHON is
used to find the Python headers and libraries. It can be either
the name of a Python executable, or the name of the directory in
which Python is installed.
'--with-guile[=GUILE]''
Build GDB with GNU Guile scripting support. (Done by default if
libguile is present and found at configure time.) If your host
does not have Guile installed, you can find it at
'https://www.gnu.org/software/guile/'. The optional argument GUILE
can be a version number, which will cause 'configure' to try to use
that version of Guile; or the file name of a 'pkg-config'
executable, which will be queried to find the information needed to
compile and link against Guile.
'--without-included-regex'
Don't use the regex library included with GDB (as part of the
libiberty library). This is the default on hosts with version 2 of
the GNU C library.
'--with-sysroot=DIR'
Use DIR as the default system root directory for libraries whose
file names begin with '/lib'' or '/usr/lib''. (The value of DIR
can be modified at run time by using the 'set sysroot' command.)
If DIR is under the GDB configured prefix (set with '--prefix' or
'--exec-prefix options', the default system root will be
automatically adjusted if and when GDB is moved to a different
location.
'--with-system-gdbinit=FILE'
Configure GDB to automatically load a system-wide init file. FILE
should be an absolute file name. If FILE is in a directory under
the configured prefix, and GDB is moved to another location after
being built, the location of the system-wide init file will be
adjusted accordingly.
'--with-system-gdbinit-dir=DIRECTORY'
Configure GDB to automatically load init files from a system-wide
directory. DIRECTORY should be an absolute directory name. If
DIRECTORY is in a directory under the configured prefix, and GDB is
moved to another location after being built, the location of the
system-wide init directory will be adjusted accordingly.
'--enable-build-warnings'
When building the GDB sources, ask the compiler to warn about any
code which looks even vaguely suspicious. It passes many different
warning flags, depending on the exact version of the compiler you
are using.
'--enable-werror'
Treat compiler warnings as werrors. It adds the '-Werror' flag to
the compiler, which will fail the compilation if the compiler
outputs any warning messages.
'--enable-ubsan'
Enable the GCC undefined behavior sanitizer. This is disabled by
default, but passing '--enable-ubsan=yes' or '--enable-ubsan=auto'
to 'configure' will enable it. The undefined behavior sanitizer
checks for C++ undefined behavior. It has a performance cost, so
if you are looking at GDB's performance, you should disable it.
The undefined behavior sanitizer was first introduced in GCC 4.9.

File: gdb.info, Node: System-wide configuration, Prev: Configure Options, Up: Installing GDB
C.6 System-wide configuration and settings
==========================================
GDB can be configured to have a system-wide init file and a system-wide
init file directory; this file and files in that directory (if they have
a recognized file extension) will be read and executed at startup (*note
What GDB does during startup: Startup.).
Here are the corresponding configure options:
'--with-system-gdbinit=FILE'
Specify that the default location of the system-wide init file is
FILE.
'--with-system-gdbinit-dir=DIRECTORY'
Specify that the default location of the system-wide init file
directory is DIRECTORY.
If GDB has been configured with the option '--prefix=$prefix', they
may be subject to relocation. Two possible cases:
* If the default location of this init file/directory contains
'$prefix', it will be subject to relocation. Suppose that the
configure options are '--prefix=$prefix
--with-system-gdbinit=$prefix/etc/gdbinit'; if GDB is moved from
'$prefix' to '$install', the system init file is looked for as
'$install/etc/gdbinit' instead of '$prefix/etc/gdbinit'.
* By contrast, if the default location does not contain the prefix,
it will not be relocated. E.g. if GDB has been configured with
'--prefix=/usr/local --with-system-gdbinit=/usr/share/gdb/gdbinit',
then GDB will always look for '/usr/share/gdb/gdbinit', wherever
GDB is installed.
If the configured location of the system-wide init file (as given by
the '--with-system-gdbinit' option at configure time) is in the
data-directory (as specified by '--with-gdb-datadir' at configure time)
or in one of its subdirectories, then GDB will look for the system-wide
init file in the directory specified by the '--data-directory'
command-line option. Note that the system-wide init file is only read
once, during GDB initialization. If the data-directory is changed after
GDB has started with the 'set data-directory' command, the file will not
be reread.
This applies similarly to the system-wide directory specified in
'--with-system-gdbinit-dir'.
Any supported scripting language can be used for these init files, as
long as the file extension matches the scripting language. To be
interpreted as regular GDB commands, the files needs to have a '.gdb'
extension.
* Menu:
* System-wide Configuration Scripts:: Installed System-wide Configuration Scripts

File: gdb.info, Node: System-wide Configuration Scripts, Up: System-wide configuration
C.6.1 Installed System-wide Configuration Scripts
-------------------------------------------------
The 'system-gdbinit' directory, located inside the data-directory (as
specified by '--with-gdb-datadir' at configure time) contains a number
of scripts which can be used as system-wide init files. To
automatically source those scripts at startup, GDB should be configured
with '--with-system-gdbinit'. Otherwise, any user should be able to
source them by hand as needed.
The following scripts are currently available:
* 'elinos.py' This script is useful when debugging a program on an
ELinOS target. It takes advantage of the environment variables
defined in a standard ELinOS environment in order to determine the
location of the system shared libraries, and then sets the
'solib-absolute-prefix' and 'solib-search-path' variables
appropriately.
* 'wrs-linux.py' This script is useful when debugging a program on a
target running Wind River Linux. It expects the 'ENV_PREFIX' to be
set to the host-side sysroot used by the target system.

File: gdb.info, Node: Maintenance Commands, Next: Remote Protocol, Prev: Installing GDB, Up: Top
Appendix D Maintenance Commands
*******************************
In addition to commands intended for GDB users, GDB includes a number of
commands intended for GDB developers, that are not documented elsewhere
in this manual. These commands are provided here for reference. (For
commands that turn on debugging messages, see *note Debugging Output::.)
'maint agent [-at LOCATION,] EXPRESSION'
'maint agent-eval [-at LOCATION,] EXPRESSION'
Translate the given EXPRESSION into remote agent bytecodes. This
command is useful for debugging the Agent Expression mechanism
(*note Agent Expressions::). The 'agent' version produces an
expression useful for data collection, such as by tracepoints,
while 'maint agent-eval' produces an expression that evaluates
directly to a result. For instance, a collection expression for
'globa + globb' will include bytecodes to record four bytes of
memory at each of the addresses of 'globa' and 'globb', while
discarding the result of the addition, while an evaluation
expression will do the addition and return the sum. If '-at' is
given, generate remote agent bytecode for LOCATION. If not,
generate remote agent bytecode for current frame PC address.
'maint agent-printf FORMAT,EXPR,...'
Translate the given format string and list of argument expressions
into remote agent bytecodes and display them as a disassembled
list. This command is useful for debugging the agent version of
dynamic printf (*note Dynamic Printf::).
'maint info breakpoints'
Using the same format as 'info breakpoints', display both the
breakpoints you've set explicitly, and those GDB is using for
internal purposes. Internal breakpoints are shown with negative
breakpoint numbers. The type column identifies what kind of
breakpoint is shown:
'breakpoint'
Normal, explicitly set breakpoint.
'watchpoint'
Normal, explicitly set watchpoint.
'longjmp'
Internal breakpoint, used to handle correctly stepping through
'longjmp' calls.
'longjmp resume'
Internal breakpoint at the target of a 'longjmp'.
'until'
Temporary internal breakpoint used by the GDB 'until' command.
'finish'
Temporary internal breakpoint used by the GDB 'finish'
command.
'shlib events'
Shared library events.
'maint info btrace'
Pint information about raw branch tracing data.
'maint btrace packet-history'
Print the raw branch trace packets that are used to compute the
execution history for the 'record btrace' command. Both the
information and the format in which it is printed depend on the
btrace recording format.
'bts'
For the BTS recording format, print a list of blocks of
sequential code. For each block, the following information is
printed:
Block number
Newer blocks have higher numbers. The oldest block has
number zero.
Lowest 'PC'
Highest 'PC'
'pt'
For the Intel Processor Trace recording format, print a list
of Intel Processor Trace packets. For each packet, the
following information is printed:
Packet number
Newer packets have higher numbers. The oldest packet has
number zero.
Trace offset
The packet's offset in the trace stream.
Packet opcode and payload
'maint btrace clear-packet-history'
Discards the cached packet history printed by the 'maint btrace
packet-history' command. The history will be computed again when
needed.
'maint btrace clear'
Discard the branch trace data. The data will be fetched anew and
the branch trace will be recomputed when needed.
This implicitly truncates the branch trace to a single branch trace
buffer. When updating branch trace incrementally, the branch trace
available to GDB may be bigger than a single branch trace buffer.
'maint set btrace pt skip-pad'
'maint show btrace pt skip-pad'
Control whether GDB will skip PAD packets when computing the packet
history.
'set displaced-stepping'
'show displaced-stepping'
Control whether or not GDB will do "displaced stepping" if the
target supports it. Displaced stepping is a way to single-step
over breakpoints without removing them from the inferior, by
executing an out-of-line copy of the instruction that was
originally at the breakpoint location. It is also known as
out-of-line single-stepping.
'set displaced-stepping on'
If the target architecture supports it, GDB will use displaced
stepping to step over breakpoints.
'set displaced-stepping off'
GDB will not use displaced stepping to step over breakpoints,
even if such is supported by the target architecture.
'set displaced-stepping auto'
This is the default mode. GDB will use displaced stepping
only if non-stop mode is active (*note Non-Stop Mode::) and
the target architecture supports displaced stepping.
'maint check-psymtabs'
Check the consistency of currently expanded psymtabs versus
symtabs. Use this to check, for example, whether a symbol is in
one but not the other.
'maint check-symtabs'
Check the consistency of currently expanded symtabs.
'maint expand-symtabs [REGEXP]'
Expand symbol tables. If REGEXP is specified, only expand symbol
tables for file names matching REGEXP.
'maint set catch-demangler-crashes [on|off]'
'maint show catch-demangler-crashes'
Control whether GDB should attempt to catch crashes in the symbol
name demangler. The default is to attempt to catch crashes. If
enabled, the first time a crash is caught, a core file is created,
the offending symbol is displayed and the user is presented with
the option to terminate the current session.
'maint cplus first_component NAME'
Print the first C++ class/namespace component of NAME.
'maint cplus namespace'
Print the list of possible C++ namespaces.
'maint deprecate COMMAND [REPLACEMENT]'
'maint undeprecate COMMAND'
Deprecate or undeprecate the named COMMAND. Deprecated commands
cause GDB to issue a warning when you use them. The optional
argument REPLACEMENT says which newer command should be used in
favor of the deprecated one; if it is given, GDB will mention the
replacement as part of the warning.
'maint dump-me'
Cause a fatal signal in the debugger and force it to dump its core.
This is supported only on systems which support aborting a program
with the 'SIGQUIT' signal.
'maint internal-error [MESSAGE-TEXT]'
'maint internal-warning [MESSAGE-TEXT]'
'maint demangler-warning [MESSAGE-TEXT]'
Cause GDB to call the internal function 'internal_error',
'internal_warning' or 'demangler_warning' and hence behave as
though an internal problem has been detected. In addition to
reporting the internal problem, these functions give the user the
opportunity to either quit GDB or (for 'internal_error' and
'internal_warning') create a core file of the current GDB session.
These commands take an optional parameter MESSAGE-TEXT that is used
as the text of the error or warning message.
Here's an example of using 'internal-error':
(gdb) maint internal-error testing, 1, 2
.../maint.c:121: internal-error: testing, 1, 2
A problem internal to GDB has been detected. Further
debugging may prove unreliable.
Quit this debugging session? (y or n) n
Create a core file? (y or n) n
(gdb)
'maint set internal-error ACTION [ask|yes|no]'
'maint show internal-error ACTION'
'maint set internal-warning ACTION [ask|yes|no]'
'maint show internal-warning ACTION'
'maint set demangler-warning ACTION [ask|yes|no]'
'maint show demangler-warning ACTION'
When GDB reports an internal problem (error or warning) it gives
the user the opportunity to both quit GDB and create a core file of
the current GDB session. These commands let you override the
default behaviour for each particular ACTION, described in the
table below.
'quit'
You can specify that GDB should always (yes) or never (no)
quit. The default is to ask the user what to do.
'corefile'
You can specify that GDB should always (yes) or never (no)
create a core file. The default is to ask the user what to
do. Note that there is no 'corefile' option for
'demangler-warning': demangler warnings always create a core
file and this cannot be disabled.
'maint packet TEXT'
If GDB is talking to an inferior via the serial protocol, then this
command sends the string TEXT to the inferior, and displays the
response packet. GDB supplies the initial '$' character, the
terminating '#' character, and the checksum.
'maint print architecture [FILE]'
Print the entire architecture configuration. The optional argument
FILE names the file where the output goes.
'maint print c-tdesc'
Print the target description (*note Target Descriptions::) as a C
source file. By default, the target description is for the current
target, but if the optional argument FILE is provided, that file is
used to produce the description. The FILE should be an XML
document, of the form described in *note Target Description
Format::. The created source file is built into GDB when GDB is
built again. This command is used by developers after they add or
modify XML target descriptions.
'maint check xml-descriptions DIR'
Check that the target descriptions dynamically created by GDB equal
the descriptions created from XML files found in DIR.
'maint check libthread-db'
Run integrity checks on the current inferior's thread debugging
library. This exercises all 'libthread_db' functionality used by
GDB on GNU/Linux systems, and by extension also exercises the
'proc_service' functions provided by GDB that 'libthread_db' uses.
Note that parts of the test may be skipped on some platforms when
debugging core files.
'maint print dummy-frames'
Prints the contents of GDB's internal dummy-frame stack.
(gdb) b add
...
(gdb) print add(2,3)
Breakpoint 2, add (a=2, b=3) at ...
58 return (a + b);
The program being debugged stopped while in a function called from GDB.
...
(gdb) maint print dummy-frames
0xa8206d8: id={stack=0xbfffe734,code=0xbfffe73f,!special}, ptid=process 9353
(gdb)
Takes an optional file parameter.
'maint print registers [FILE]'
'maint print raw-registers [FILE]'
'maint print cooked-registers [FILE]'
'maint print register-groups [FILE]'
'maint print remote-registers [FILE]'
Print GDB's internal register data structures.
The command 'maint print raw-registers' includes the contents of
the raw register cache; the command 'maint print cooked-registers'
includes the (cooked) value of all registers, including registers
which aren't available on the target nor visible to user; the
command 'maint print register-groups' includes the groups that each
register is a member of; and the command 'maint print
remote-registers' includes the remote target's register numbers and
offsets in the 'G' packets.
These commands take an optional parameter, a file name to which to
write the information.
'maint print reggroups [FILE]'
Print GDB's internal register group data structures. The optional
argument FILE tells to what file to write the information.
The register groups info looks like this:
(gdb) maint print reggroups
Group Type
general user
float user
all user
vector user
system user
save internal
restore internal
'flushregs'
This command forces GDB to flush its internal register cache.
'maint print objfiles [REGEXP]'
Print a dump of all known object files. If REGEXP is specified,
only print object files whose names match REGEXP. For each object
file, this command prints its name, address in memory, and all of
its psymtabs and symtabs.
'maint print user-registers'
List all currently available "user registers". User registers
typically provide alternate names for actual hardware registers.
They include the four "standard" registers '$fp', '$pc', '$sp', and
'$ps'. *Note standard registers::. User registers can be used in
expressions in the same way as the canonical register names, but
only the latter are listed by the 'info registers' and 'maint print
registers' commands.
'maint print section-scripts [REGEXP]'
Print a dump of scripts specified in the '.debug_gdb_section'
section. If REGEXP is specified, only print scripts loaded by
object files matching REGEXP. For each script, this command prints
its name as specified in the objfile, and the full path if known.
*Note dotdebug_gdb_scripts section::.
'maint print statistics'
This command prints, for each object file in the program, various
data about that object file followed by the byte cache ("bcache")
statistics for the object file. The objfile data includes the
number of minimal, partial, full, and stabs symbols, the number of
types defined by the objfile, the number of as yet unexpanded psym
tables, the number of line tables and string tables, and the amount
of memory used by the various tables. The bcache statistics
include the counts, sizes, and counts of duplicates of all and
unique objects, max, average, and median entry size, total memory
used and its overhead and savings, and various measures of the hash
table size and chain lengths.
'maint print target-stack'
A "target" is an interface between the debugger and a particular
kind of file or process. Targets can be stacked in "strata", so
that more than one target can potentially respond to a request. In
particular, memory accesses will walk down the stack of targets
until they find a target that is interested in handling that
particular address.
This command prints a short description of each layer that was
pushed on the "target stack", starting from the top layer down to
the bottom one.
'maint print type EXPR'
Print the type chain for a type specified by EXPR. The argument
can be either a type name or a symbol. If it is a symbol, the type
of that symbol is described. The type chain produced by this
command is a recursive definition of the data type as stored in
GDB's data structures, including its flags and contained types.
'maint selftest [FILTER]'
Run any self tests that were compiled in to GDB. This will print a
message showing how many tests were run, and how many failed. If a
FILTER is passed, only the tests with FILTER in their name will by
ran.
'maint info selftests'
List the selftests compiled in to GDB.
'maint set dwarf always-disassemble'
'maint show dwarf always-disassemble'
Control the behavior of 'info address' when using DWARF debugging
information.
The default is 'off', which means that GDB should try to describe a
variable's location in an easily readable format. When 'on', GDB
will instead display the DWARF location expression in an
assembly-like format. Note that some locations are too complex for
GDB to describe simply; in this case you will always see the
disassembly form.
Here is an example of the resulting disassembly:
(gdb) info addr argc
Symbol "argc" is a complex DWARF expression:
1: DW_OP_fbreg 0
For more information on these expressions, see the DWARF standard
(http://www.dwarfstd.org/).
'maint set dwarf max-cache-age'
'maint show dwarf max-cache-age'
Control the DWARF compilation unit cache.
In object files with inter-compilation-unit references, such as
those produced by the GCC option '-feliminate-dwarf2-dups', the
DWARF reader needs to frequently refer to previously read
compilation units. This setting controls how long a compilation
unit will remain in the cache if it is not referenced. A higher
limit means that cached compilation units will be stored in memory
longer, and more total memory will be used. Setting it to zero
disables caching, which will slow down GDB startup, but reduce
memory consumption.
'maint set dwarf unwinders'
'maint show dwarf unwinders'
Control use of the DWARF frame unwinders.
Many targets that support DWARF debugging use GDB's DWARF frame
unwinders to build the backtrace. Many of these targets will also
have a second mechanism for building the backtrace for use in cases
where DWARF information is not available, this second mechanism is
often an analysis of a function's prologue.
In order to extend testing coverage of the second level stack
unwinding mechanisms it is helpful to be able to disable the DWARF
stack unwinders, this can be done with this switch.
In normal use of GDB disabling the DWARF unwinders is not
advisable, there are cases that are better handled through DWARF
than prologue analysis, and the debug experience is likely to be
better with the DWARF frame unwinders enabled.
If DWARF frame unwinders are not supported for a particular target
architecture, then enabling this flag does not cause them to be
used.
'maint set worker-threads'
'maint show worker-threads'
Control the number of worker threads that may be used by GDB. On
capable hosts, GDB may use multiple threads to speed up certain
CPU-intensive operations, such as demangling symbol names. While
the number of threads used by GDB may vary, this command can be
used to set an upper bound on this number. The default is '0'
(disabled). A value of 'unlimited' lets GDB choose a reasonable
number. Note that this only controls worker threads started by GDB
itself; libraries used by GDB may start threads of their own.
'maint set profile'
'maint show profile'
Control profiling of GDB.
Profiling will be disabled until you use the 'maint set profile'
command to enable it. When you enable profiling, the system will
begin collecting timing and execution count data; when you disable
profiling or exit GDB, the results will be written to a log file.
Remember that if you use profiling, GDB will overwrite the
profiling log file (often called 'gmon.out'). If you have a record
of important profiling data in a 'gmon.out' file, be sure to move
it to a safe location.
Configuring with '--enable-profiling' arranges for GDB to be
compiled with the '-pg' compiler option.
'maint set show-debug-regs'
'maint show show-debug-regs'
Control whether to show variables that mirror the hardware debug
registers. Use 'on' to enable, 'off' to disable. If enabled, the
debug registers values are shown when GDB inserts or removes a
hardware breakpoint or watchpoint, and when the inferior triggers a
hardware-assisted breakpoint or watchpoint.
'maint set show-all-tib'
'maint show show-all-tib'
Control whether to show all non zero areas within a 1k block
starting at thread local base, when using the 'info w32
thread-information-block' command.
'maint set target-async'
'maint show target-async'
This controls whether GDB targets operate in synchronous or
asynchronous mode (*note Background Execution::). Normally the
default is asynchronous, if it is available; but this can be
changed to more easily debug problems occurring only in synchronous
mode.
'maint set target-non-stop'
'maint show target-non-stop'
This controls whether GDB targets always operate in non-stop mode
even if 'set non-stop' is 'off' (*note Non-Stop Mode::). The
default is 'auto', meaning non-stop mode is enabled if supported by
the target.
'maint set target-non-stop auto'
This is the default mode. GDB controls the target in non-stop
mode if the target supports it.
'maint set target-non-stop on'
GDB controls the target in non-stop mode even if the target
does not indicate support.
'maint set target-non-stop off'
GDB does not control the target in non-stop mode even if the
target supports it.
'maint set tui-resize-message'
'maint show tui-resize-message'
Control whether GDB displays a message each time the terminal is
resized when in TUI mode. The default is 'off', which means that
GDB is silent during resizes. When 'on', GDB will display a
message after a resize is completed; the message will include a
number indicating how many times the terminal has been resized.
This setting is intended for use by the test suite, where it would
otherwise be difficult to determine when a resize and refresh has
been completed.
'maint set per-command'
'maint show per-command'
GDB can display the resources used by each command. This is useful
in debugging performance problems.
'maint set per-command space [on|off]'
'maint show per-command space'
Enable or disable the printing of the memory used by GDB for
each command. If enabled, GDB will display how much memory
each command took, following the command's own output. This
can also be requested by invoking GDB with the '--statistics'
command-line switch (*note Mode Options::).
'maint set per-command time [on|off]'
'maint show per-command time'
Enable or disable the printing of the execution time of GDB
for each command. If enabled, GDB will display how much time
it took to execute each command, following the command's own
output. Both CPU time and wallclock time are printed.
Printing both is useful when trying to determine whether the
cost is CPU or, e.g., disk/network latency. Note that the CPU
time printed is for GDB only, it does not include the
execution time of the inferior because there's no mechanism
currently to compute how much time was spent by GDB and how
much time was spent by the program been debugged. This can
also be requested by invoking GDB with the '--statistics'
command-line switch (*note Mode Options::).
'maint set per-command symtab [on|off]'
'maint show per-command symtab'
Enable or disable the printing of basic symbol table
statistics for each command. If enabled, GDB will display the
following information:
a. number of symbol tables
b. number of primary symbol tables
c. number of blocks in the blockvector
'maint set check-libthread-db [on|off]'
'maint show check-libthread-db'
Control whether GDB should run integrity checks on inferior
specific thread debugging libraries as they are loaded. The
default is not to perform such checks. If any check fails GDB will
unload the library and continue searching for a suitable candidate
as described in *note set libthread-db-search-path::. For more
information about the tests, see *note maint check libthread-db::.
'maint space VALUE'
An alias for 'maint set per-command space'. A non-zero value
enables it, zero disables it.
'maint time VALUE'
An alias for 'maint set per-command time'. A non-zero value
enables it, zero disables it.
'maint translate-address [SECTION] ADDR'
Find the symbol stored at the location specified by the address
ADDR and an optional section name SECTION. If found, GDB prints
the name of the closest symbol and an offset from the symbol's
location to the specified address. This is similar to the 'info
address' command (*note Symbols::), except that this command also
allows to find symbols in other sections.
If section was not specified, the section in which the symbol was
found is also printed. For dynamically linked executables, the
name of executable or shared library containing the symbol is
printed as well.
'maint test-options require-delimiter'
'maint test-options unknown-is-error'
'maint test-options unknown-is-operand'
These commands are used by the testsuite to validate the command
options framework. The 'require-delimiter' variant requires a
double-dash delimiter to indicate end of options. The
'unknown-is-error' and 'unknown-is-operand' do not. The
'unknown-is-error' variant throws an error on unknown option, while
'unknown-is-operand' treats unknown options as the start of the
command's operands. When run, the commands output the result of
the processed options. When completed, the commands store the
internal result of completion in a variable exposed by the 'maint
show test-options-completion-result' command.
'maint show test-options-completion-result'
Shows the result of completing the 'maint test-options'
subcommands. This is used by the testsuite to validate completion
support in the command options framework.
'maint set test-settings KIND'
'maint show test-settings KIND'
These are representative commands for each KIND of setting type GDB
supports. They are used by the testsuite for exercising the
settings infrastructure.
'maint with SETTING [VALUE] [-- COMMAND]'
Like the 'with' command, but works with 'maintenance set'
variables. This is used by the testsuite to exercise the 'with'
command's infrastructure.
The following command is useful for non-interactive invocations of
GDB, such as in the test suite.
'set watchdog NSEC'
Set the maximum number of seconds GDB will wait for the target
operation to finish. If this time expires, GDB reports and error
and the command is aborted.
'show watchdog'
Show the current setting of the target wait timeout.

File: gdb.info, Node: Remote Protocol, Next: Agent Expressions, Prev: Maintenance Commands, Up: Top
Appendix E GDB Remote Serial Protocol
*************************************
* Menu:
* Overview::
* Packets::
* Stop Reply Packets::
* General Query Packets::
* Architecture-Specific Protocol Details::
* Tracepoint Packets::
* Host I/O Packets::
* Interrupts::
* Notification Packets::
* Remote Non-Stop::
* Packet Acknowledgment::
* Examples::
* File-I/O Remote Protocol Extension::
* Library List Format::
* Library List Format for SVR4 Targets::
* Memory Map Format::
* Thread List Format::
* Traceframe Info Format::
* Branch Trace Format::
* Branch Trace Configuration Format::

File: gdb.info, Node: Overview, Next: Packets, Up: Remote Protocol
E.1 Overview
============
There may be occasions when you need to know something about the
protocol--for example, if there is only one serial port to your target
machine, you might want your program to do something special if it
recognizes a packet meant for GDB.
In the examples below, '->' and '<-' are used to indicate transmitted
and received data, respectively.
All GDB commands and responses (other than acknowledgments and
notifications, see *note Notification Packets::) are sent as a PACKET.
A PACKET is introduced with the character '$', the actual PACKET-DATA,
and the terminating character '#' followed by a two-digit CHECKSUM:
$PACKET-DATA#CHECKSUM
The two-digit CHECKSUM is computed as the modulo 256 sum of all
characters between the leading '$' and the trailing '#' (an eight bit
unsigned checksum).
Implementors should note that prior to GDB 5.0 the protocol
specification also included an optional two-digit SEQUENCE-ID:
$SEQUENCE-ID:PACKET-DATA#CHECKSUM
That SEQUENCE-ID was appended to the acknowledgment. GDB has never
output SEQUENCE-IDs. Stubs that handle packets added since GDB 5.0 must
not accept SEQUENCE-ID.
When either the host or the target machine receives a packet, the
first response expected is an acknowledgment: either '+' (to indicate
the package was received correctly) or '-' (to request retransmission):
-> $PACKET-DATA#CHECKSUM
<- +
The '+'/'-' acknowledgments can be disabled once a connection is
established. *Note Packet Acknowledgment::, for details.
The host (GDB) sends COMMANDs, and the target (the debugging stub
incorporated in your program) sends a RESPONSE. In the case of step and
continue COMMANDs, the response is only sent when the operation has
completed, and the target has again stopped all threads in all attached
processes. This is the default all-stop mode behavior, but the remote
protocol also supports GDB's non-stop execution mode; see *note Remote
Non-Stop::, for details.
PACKET-DATA consists of a sequence of characters with the exception
of '#' and '$' (see 'X' packet for additional exceptions).
Fields within the packet should be separated using ',' ';' or ':'.
Except where otherwise noted all numbers are represented in HEX with
leading zeros suppressed.
Implementors should note that prior to GDB 5.0, the character ':'
could not appear as the third character in a packet (as it would
potentially conflict with the SEQUENCE-ID).
Binary data in most packets is encoded either as two hexadecimal
digits per byte of binary data. This allowed the traditional remote
protocol to work over connections which were only seven-bit clean. Some
packets designed more recently assume an eight-bit clean connection, and
use a more efficient encoding to send and receive binary data.
The binary data representation uses '7d' (ASCII '}') as an escape
character. Any escaped byte is transmitted as the escape character
followed by the original character XORed with '0x20'. For example, the
byte '0x7d' would be transmitted as the two bytes '0x7d 0x5d'. The
bytes '0x23' (ASCII '#'), '0x24' (ASCII '$'), and '0x7d' (ASCII '}')
must always be escaped. Responses sent by the stub must also escape
'0x2a' (ASCII '*'), so that it is not interpreted as the start of a
run-length encoded sequence (described next).
Response DATA can be run-length encoded to save space. Run-length
encoding replaces runs of identical characters with one instance of the
repeated character, followed by a '*' and a repeat count. The repeat
count is itself sent encoded, to avoid binary characters in DATA: a
value of N is sent as 'N+29'. For a repeat count greater or equal to 3,
this produces a printable ASCII character, e.g. a space (ASCII code 32)
for a repeat count of 3. (This is because run-length encoding starts to
win for counts 3 or more.) Thus, for example, '0* ' is a run-length
encoding of "0000": the space character after '*' means repeat the
leading '0' '32 - 29 = 3' more times.
The printable characters '#' and '$' or with a numeric value greater
than 126 must not be used. Runs of six repeats ('#') or seven repeats
('$') can be expanded using a repeat count of only five ('"'). For
example, '00000000' can be encoded as '0*"00'.
The error response returned for some packets includes a two character
error number. That number is not well defined.
For any COMMAND not supported by the stub, an empty response ('$#00')
should be returned. That way it is possible to extend the protocol. A
newer GDB can tell if a packet is supported based on that response.
At a minimum, a stub is required to support the 'g' and 'G' commands
for register access, and the 'm' and 'M' commands for memory access.
Stubs that only control single-threaded targets can implement run
control with the 'c' (continue), and 's' (step) commands. Stubs that
support multi-threading targets should support the 'vCont' command. All
other commands are optional.

File: gdb.info, Node: Packets, Next: Stop Reply Packets, Prev: Overview, Up: Remote Protocol
E.2 Packets
===========
The following table provides a complete list of all currently defined
COMMANDs and their corresponding response DATA. *Note File-I/O Remote
Protocol Extension::, for details about the File I/O extension of the
remote protocol.
Each packet's description has a template showing the packet's overall
syntax, followed by an explanation of the packet's meaning. We include
spaces in some of the templates for clarity; these are not part of the
packet's syntax. No GDB packet uses spaces to separate its components.
For example, a template like 'foo BAR BAZ' describes a packet beginning
with the three ASCII bytes 'foo', followed by a BAR, followed directly
by a BAZ. GDB does not transmit a space character between the 'foo' and
the BAR, or between the BAR and the BAZ.
Several packets and replies include a THREAD-ID field to identify a
thread. Normally these are positive numbers with a target-specific
interpretation, formatted as big-endian hex strings. A THREAD-ID can
also be a literal '-1' to indicate all threads, or '0' to pick any
thread.
In addition, the remote protocol supports a multiprocess feature in
which the THREAD-ID syntax is extended to optionally include both
process and thread ID fields, as 'pPID.TID'. The PID (process) and TID
(thread) components each have the format described above: a positive
number with target-specific interpretation formatted as a big-endian hex
string, literal '-1' to indicate all processes or threads
(respectively), or '0' to indicate an arbitrary process or thread.
Specifying just a process, as 'pPID', is equivalent to 'pPID.-1'. It is
an error to specify all processes but a specific thread, such as
'p-1.TID'. Note that the 'p' prefix is _not_ used for those packets and
replies explicitly documented to include a process ID, rather than a
THREAD-ID.
The multiprocess THREAD-ID syntax extensions are only used if both
GDB and the stub report support for the 'multiprocess' feature using
'qSupported'. *Note multiprocess extensions::, for more information.
Note that all packet forms beginning with an upper- or lower-case
letter, other than those described here, are reserved for future use.
Here are the packet descriptions.
'!'
Enable extended mode. In extended mode, the remote server is made
persistent. The 'R' packet is used to restart the program being
debugged.
Reply:
'OK'
The remote target both supports and has enabled extended mode.
'?'
Indicate the reason the target halted. The reply is the same as
for step and continue. This packet has a special interpretation
when the target is in non-stop mode; see *note Remote Non-Stop::.
Reply: *Note Stop Reply Packets::, for the reply specifications.
'A ARGLEN,ARGNUM,ARG,...'
Initialized 'argv[]' array passed into program. ARGLEN specifies
the number of bytes in the hex encoded byte stream ARG. See
'gdbserver' for more details.
Reply:
'OK'
The arguments were set.
'E NN'
An error occurred.
'b BAUD'
(Don't use this packet; its behavior is not well-defined.) Change
the serial line speed to BAUD.
JTC: _When does the transport layer state change? When it's
received, or after the ACK is transmitted. In either case, there
are problems if the command or the acknowledgment packet is
dropped._
Stan: _If people really wanted to add something like this, and get
it working for the first time, they ought to modify ser-unix.c to
send some kind of out-of-band message to a specially-setup stub and
have the switch happen "in between" packets, so that from remote
protocol's point of view, nothing actually happened._
'B ADDR,MODE'
Set (MODE is 'S') or clear (MODE is 'C') a breakpoint at ADDR.
Don't use this packet. Use the 'Z' and 'z' packets instead (*note
insert breakpoint or watchpoint packet::).
'bc'
Backward continue. Execute the target system in reverse. No
parameter. *Note Reverse Execution::, for more information.
Reply: *Note Stop Reply Packets::, for the reply specifications.
'bs'
Backward single step. Execute one instruction in reverse. No
parameter. *Note Reverse Execution::, for more information.
Reply: *Note Stop Reply Packets::, for the reply specifications.
'c [ADDR]'
Continue at ADDR, which is the address to resume. If ADDR is
omitted, resume at current address.
This packet is deprecated for multi-threading support. *Note vCont
packet::.
Reply: *Note Stop Reply Packets::, for the reply specifications.
'C SIG[;ADDR]'
Continue with signal SIG (hex signal number). If ';ADDR' is
omitted, resume at same address.
This packet is deprecated for multi-threading support. *Note vCont
packet::.
Reply: *Note Stop Reply Packets::, for the reply specifications.
'd'
Toggle debug flag.
Don't use this packet; instead, define a general set packet (*note
General Query Packets::).
'D'
'D;PID'
The first form of the packet is used to detach GDB from the remote
system. It is sent to the remote target before GDB disconnects via
the 'detach' command.
The second form, including a process ID, is used when multiprocess
protocol extensions are enabled (*note multiprocess extensions::),
to detach only a specific process. The PID is specified as a
big-endian hex string.
Reply:
'OK'
for success
'E NN'
for an error
'F RC,EE,CF;XX'
A reply from GDB to an 'F' packet sent by the target. This is part
of the File-I/O protocol extension. *Note File-I/O Remote Protocol
Extension::, for the specification.
'g'
Read general registers.
Reply:
'XX...'
Each byte of register data is described by two hex digits.
The bytes with the register are transmitted in target byte
order. The size of each register and their position within
the 'g' packet are determined by the GDB internal gdbarch
functions 'DEPRECATED_REGISTER_RAW_SIZE' and
'gdbarch_register_name'.
When reading registers from a trace frame (*note Using the
Collected Data: Analyze Collected Data.), the stub may also
return a string of literal 'x''s in place of the register data
digits, to indicate that the corresponding register has not
been collected, thus its value is unavailable. For example,
for an architecture with 4 registers of 4 bytes each, the
following reply indicates to GDB that registers 0 and 2 have
not been collected, while registers 1 and 3 have been
collected, and both have zero value:
-> g
<- xxxxxxxx00000000xxxxxxxx00000000
'E NN'
for an error.
'G XX...'
Write general registers. *Note read registers packet::, for a
description of the XX... data.
Reply:
'OK'
for success
'E NN'
for an error
'H OP THREAD-ID'
Set thread for subsequent operations ('m', 'M', 'g', 'G', et.al.).
Depending on the operation to be performed, OP should be 'c' for
step and continue operations (note that this is deprecated,
supporting the 'vCont' command is a better option), and 'g' for
other operations. The thread designator THREAD-ID has the format
and interpretation described in *note thread-id syntax::.
Reply:
'OK'
for success
'E NN'
for an error
'i [ADDR[,NNN]]'
Step the remote target by a single clock cycle. If ',NNN' is
present, cycle step NNN cycles. If ADDR is present, cycle step
starting at that address.
'I'
Signal, then cycle step. *Note step with signal packet::. *Note
cycle step packet::.
'k'
Kill request.
The exact effect of this packet is not specified.
For a bare-metal target, it may power cycle or reset the target
system. For that reason, the 'k' packet has no reply.
For a single-process target, it may kill that process if possible.
A multiple-process target may choose to kill just one process, or
all that are under GDB's control. For more precise control, use
the vKill packet (*note vKill packet::).
If the target system immediately closes the connection in response
to 'k', GDB does not consider the lack of packet acknowledgment to
be an error, and assumes the kill was successful.
If connected using 'target extended-remote', and the target does
not close the connection in response to a kill request, GDB probes
the target state as if a new connection was opened (*note ?
packet::).
'm ADDR,LENGTH'
Read LENGTH addressable memory units starting at address ADDR
(*note addressable memory unit::). Note that ADDR may not be
aligned to any particular boundary.
The stub need not use any particular size or alignment when
gathering data from memory for the response; even if ADDR is
word-aligned and LENGTH is a multiple of the word size, the stub is
free to use byte accesses, or not. For this reason, this packet
may not be suitable for accessing memory-mapped I/O devices.
Reply:
'XX...'
Memory contents; each byte is transmitted as a two-digit
hexadecimal number. The reply may contain fewer addressable
memory units than requested if the server was able to read
only part of the region of memory.
'E NN'
NN is errno
'M ADDR,LENGTH:XX...'
Write LENGTH addressable memory units starting at address ADDR
(*note addressable memory unit::). The data is given by XX...;
each byte is transmitted as a two-digit hexadecimal number.
Reply:
'OK'
for success
'E NN'
for an error (this includes the case where only part of the
data was written).
'p N'
Read the value of register N; N is in hex. *Note read registers
packet::, for a description of how the returned register value is
encoded.
Reply:
'XX...'
the register's value
'E NN'
for an error
''
Indicating an unrecognized QUERY.
'P N...=R...'
Write register N... with value R.... The register number N is in
hexadecimal, and R... contains two hex digits for each byte in the
register (target byte order).
Reply:
'OK'
for success
'E NN'
for an error
'q NAME PARAMS...'
'Q NAME PARAMS...'
General query ('q') and set ('Q'). These packets are described
fully in *note General Query Packets::.
'r'
Reset the entire system.
Don't use this packet; use the 'R' packet instead.
'R XX'
Restart the program being debugged. The XX, while needed, is
ignored. This packet is only available in extended mode (*note
extended mode::).
The 'R' packet has no reply.
's [ADDR]'
Single step, resuming at ADDR. If ADDR is omitted, resume at same
address.
This packet is deprecated for multi-threading support. *Note vCont
packet::.
Reply: *Note Stop Reply Packets::, for the reply specifications.
'S SIG[;ADDR]'
Step with signal. This is analogous to the 'C' packet, but
requests a single-step, rather than a normal resumption of
execution.
This packet is deprecated for multi-threading support. *Note vCont
packet::.
Reply: *Note Stop Reply Packets::, for the reply specifications.
't ADDR:PP,MM'
Search backwards starting at address ADDR for a match with pattern
PP and mask MM, both of which are are 4 byte long. There must be
at least 3 digits in ADDR.
'T THREAD-ID'
Find out if the thread THREAD-ID is alive. *Note thread-id
syntax::.
Reply:
'OK'
thread is still alive
'E NN'
thread is dead
'v'
Packets starting with 'v' are identified by a multi-letter name, up
to the first ';' or '?' (or the end of the packet).
'vAttach;PID'
Attach to a new process with the specified process ID PID. The
process ID is a hexadecimal integer identifying the process. In
all-stop mode, all threads in the attached process are stopped; in
non-stop mode, it may be attached without being stopped if that is
supported by the target.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'E NN'
for an error
'Any stop packet'
for success in all-stop mode (*note Stop Reply Packets::)
'OK'
for success in non-stop mode (*note Remote Non-Stop::)
'vCont[;ACTION[:THREAD-ID]]...'
Resume the inferior, specifying different actions for each thread.
For each inferior thread, the leftmost action with a matching
THREAD-ID is applied. Threads that don't match any action remain
in their current state. Thread IDs are specified using the syntax
described in *note thread-id syntax::. If multiprocess extensions
(*note multiprocess extensions::) are supported, actions can be
specified to match all threads in a process by using the 'pPID.-1'
form of the THREAD-ID. An action with no THREAD-ID matches all
threads. Specifying no actions is an error.
Currently supported actions are:
'c'
Continue.
'C SIG'
Continue with signal SIG. The signal SIG should be two hex
digits.
's'
Step.
'S SIG'
Step with signal SIG. The signal SIG should be two hex
digits.
't'
Stop.
'r START,END'
Step once, and then keep stepping as long as the thread stops
at addresses between START (inclusive) and END (exclusive).
The remote stub reports a stop reply when either the thread
goes out of the range or is stopped due to an unrelated
reason, such as hitting a breakpoint. *Note range stepping::.
If the range is empty (START == END), then the action becomes
equivalent to the 's' action. In other words, single-step
once, and report the stop (even if the stepped instruction
jumps to START).
(A stop reply may be sent at any point even if the PC is still
within the stepping range; for example, it is valid to
implement this packet in a degenerate way as a single
instruction step operation.)
The optional argument ADDR normally associated with the 'c', 'C',
's', and 'S' packets is not supported in 'vCont'.
The 't' action is only relevant in non-stop mode (*note Remote
Non-Stop::) and may be ignored by the stub otherwise. A stop reply
should be generated for any affected thread not already stopped.
When a thread is stopped by means of a 't' action, the
corresponding stop reply should indicate that the thread has
stopped with signal '0', regardless of whether the target uses some
other signal as an implementation detail.
The server must ignore 'c', 'C', 's', 'S', and 'r' actions for
threads that are already running. Conversely, the server must
ignore 't' actions for threads that are already stopped.
_Note:_ In non-stop mode, a thread is considered running until GDB
acknowledges an asynchronous stop notification for it with the
'vStopped' packet (*note Remote Non-Stop::).
The stub must support 'vCont' if it reports support for
multiprocess extensions (*note multiprocess extensions::).
Reply: *Note Stop Reply Packets::, for the reply specifications.
'vCont?'
Request a list of actions supported by the 'vCont' packet.
Reply:
'vCont[;ACTION...]'
The 'vCont' packet is supported. Each ACTION is a supported
command in the 'vCont' packet.
''
The 'vCont' packet is not supported.
'vCtrlC'
Interrupt remote target as if a control-C was pressed on the remote
terminal. This is the equivalent to reacting to the '^C' ('\003',
the control-C character) character in all-stop mode while the
target is running, except this works in non-stop mode. *Note
interrupting remote targets::, for more info on the all-stop
variant.
Reply:
'E NN'
for an error
'OK'
for success
'vFile:OPERATION:PARAMETER...'
Perform a file operation on the target system. For details, see
*note Host I/O Packets::.
'vFlashErase:ADDR,LENGTH'
Direct the stub to erase LENGTH bytes of flash starting at ADDR.
The region may enclose any number of flash blocks, but its start
and end must fall on block boundaries, as indicated by the flash
block size appearing in the memory map (*note Memory Map Format::).
GDB groups flash memory programming operations together, and sends
a 'vFlashDone' request after each group; the stub is allowed to
delay erase operation until the 'vFlashDone' packet is received.
Reply:
'OK'
for success
'E NN'
for an error
'vFlashWrite:ADDR:XX...'
Direct the stub to write data to flash address ADDR. The data is
passed in binary form using the same encoding as for the 'X' packet
(*note Binary Data::). The memory ranges specified by
'vFlashWrite' packets preceding a 'vFlashDone' packet must not
overlap, and must appear in order of increasing addresses (although
'vFlashErase' packets for higher addresses may already have been
received; the ordering is guaranteed only between 'vFlashWrite'
packets). If a packet writes to an address that was neither erased
by a preceding 'vFlashErase' packet nor by some other
target-specific method, the results are unpredictable.
Reply:
'OK'
for success
'E.memtype'
for vFlashWrite addressing non-flash memory
'E NN'
for an error
'vFlashDone'
Indicate to the stub that flash programming operation is finished.
The stub is permitted to delay or batch the effects of a group of
'vFlashErase' and 'vFlashWrite' packets until a 'vFlashDone' packet
is received. The contents of the affected regions of flash memory
are unpredictable until the 'vFlashDone' request is completed.
'vKill;PID'
Kill the process with the specified process ID PID, which is a
hexadecimal integer identifying the process. This packet is used
in preference to 'k' when multiprocess protocol extensions are
supported; see *note multiprocess extensions::.
Reply:
'E NN'
for an error
'OK'
for success
'vMustReplyEmpty'
The correct reply to an unknown 'v' packet is to return the empty
string, however, some older versions of 'gdbserver' would
incorrectly return 'OK' for unknown 'v' packets.
The 'vMustReplyEmpty' is used as a feature test to check how
'gdbserver' handles unknown packets, it is important that this
packet be handled in the same way as other unknown 'v' packets. If
this packet is handled differently to other unknown 'v' packets
then it is possible that GDB may run into problems in other areas,
specifically around use of 'vFile:setfs:'.
'vRun;FILENAME[;ARGUMENT]...'
Run the program FILENAME, passing it each ARGUMENT on its command
line. The file and arguments are hex-encoded strings. If FILENAME
is an empty string, the stub may use a default program (e.g. the
last program run). The program is created in the stopped state.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'E NN'
for an error
'Any stop packet'
for success (*note Stop Reply Packets::)
'vStopped'
*Note Notification Packets::.
'X ADDR,LENGTH:XX...'
Write data to memory, where the data is transmitted in binary.
Memory is specified by its address ADDR and number of addressable
memory units LENGTH (*note addressable memory unit::); 'XX...' is
binary data (*note Binary Data::).
Reply:
'OK'
for success
'E NN'
for an error
'z TYPE,ADDR,KIND'
'Z TYPE,ADDR,KIND'
Insert ('Z') or remove ('z') a TYPE breakpoint or watchpoint
starting at address ADDRESS of kind KIND.
Each breakpoint and watchpoint packet TYPE is documented
separately.
_Implementation notes: A remote target shall return an empty string
for an unrecognized breakpoint or watchpoint packet TYPE. A remote
target shall support either both or neither of a given 'ZTYPE...'
and 'zTYPE...' packet pair. To avoid potential problems with
duplicate packets, the operations should be implemented in an
idempotent way._
'z0,ADDR,KIND'
'Z0,ADDR,KIND[;COND_LIST...][;cmds:PERSIST,CMD_LIST...]'
Insert ('Z0') or remove ('z0') a software breakpoint at address
ADDR of type KIND.
A software breakpoint is implemented by replacing the instruction
at ADDR with a software breakpoint or trap instruction. The KIND
is target-specific and typically indicates the size of the
breakpoint in bytes that should be inserted. E.g., the ARM and
MIPS can insert either a 2 or 4 byte breakpoint. Some
architectures have additional meanings for KIND (*note
Architecture-Specific Protocol Details::); if no
architecture-specific value is being used, it should be '0'. KIND
is hex-encoded. COND_LIST is an optional list of conditional
expressions in bytecode form that should be evaluated on the
target's side. These are the conditions that should be taken into
consideration when deciding if the breakpoint trigger should be
reported back to GDB.
See also the 'swbreak' stop reason (*note swbreak stop reason::)
for how to best report a software breakpoint event to GDB.
The COND_LIST parameter is comprised of a series of expressions,
concatenated without separators. Each expression has the following
form:
'X LEN,EXPR'
LEN is the length of the bytecode expression and EXPR is the
actual conditional expression in bytecode form.
The optional CMD_LIST parameter introduces commands that may be run
on the target, rather than being reported back to GDB. The
parameter starts with a numeric flag PERSIST; if the flag is
nonzero, then the breakpoint may remain active and the commands
continue to be run even when GDB disconnects from the target.
Following this flag is a series of expressions concatenated with no
separators. Each expression has the following form:
'X LEN,EXPR'
LEN is the length of the bytecode expression and EXPR is the
actual commands expression in bytecode form.
_Implementation note: It is possible for a target to copy or move
code that contains software breakpoints (e.g., when implementing
overlays). The behavior of this packet, in the presence of such a
target, is not defined._
Reply:
'OK'
success
''
not supported
'E NN'
for an error
'z1,ADDR,KIND'
'Z1,ADDR,KIND[;COND_LIST...][;cmds:PERSIST,CMD_LIST...]'
Insert ('Z1') or remove ('z1') a hardware breakpoint at address
ADDR.
A hardware breakpoint is implemented using a mechanism that is not
dependent on being able to modify the target's memory. The KIND,
COND_LIST, and CMD_LIST arguments have the same meaning as in 'Z0'
packets.
_Implementation note: A hardware breakpoint is not affected by code
movement._
Reply:
'OK'
success
''
not supported
'E NN'
for an error
'z2,ADDR,KIND'
'Z2,ADDR,KIND'
Insert ('Z2') or remove ('z2') a write watchpoint at ADDR. The
number of bytes to watch is specified by KIND.
Reply:
'OK'
success
''
not supported
'E NN'
for an error
'z3,ADDR,KIND'
'Z3,ADDR,KIND'
Insert ('Z3') or remove ('z3') a read watchpoint at ADDR. The
number of bytes to watch is specified by KIND.
Reply:
'OK'
success
''
not supported
'E NN'
for an error
'z4,ADDR,KIND'
'Z4,ADDR,KIND'
Insert ('Z4') or remove ('z4') an access watchpoint at ADDR. The
number of bytes to watch is specified by KIND.
Reply:
'OK'
success
''
not supported
'E NN'
for an error

File: gdb.info, Node: Stop Reply Packets, Next: General Query Packets, Prev: Packets, Up: Remote Protocol
E.3 Stop Reply Packets
======================
The 'C', 'c', 'S', 's', 'vCont', 'vAttach', 'vRun', 'vStopped', and '?'
packets can receive any of the below as a reply. Except for '?' and
'vStopped', that reply is only returned when the target halts. In the
below the exact meaning of "signal number" is defined by the header
'include/gdb/signals.h' in the GDB source code.
In non-stop mode, the server will simply reply 'OK' to commands such
as 'vCont'; any stop will be the subject of a future notification.
*Note Remote Non-Stop::.
As in the description of request packets, we include spaces in the
reply templates for clarity; these are not part of the reply packet's
syntax. No GDB stop reply packet uses spaces to separate its
components.
'S AA'
The program received signal number AA (a two-digit hexadecimal
number). This is equivalent to a 'T' response with no N:R pairs.
'T AA N1:R1;N2:R2;...'
The program received signal number AA (a two-digit hexadecimal
number). This is equivalent to an 'S' response, except that the
'N:R' pairs can carry values of important registers and other
information directly in the stop reply packet, reducing round-trip
latency. Single-step and breakpoint traps are reported this way.
Each 'N:R' pair is interpreted as follows:
* If N is a hexadecimal number, it is a register number, and the
corresponding R gives that register's value. The data R is a
series of bytes in target byte order, with each byte given by
a two-digit hex number.
* If N is 'thread', then R is the THREAD-ID of the stopped
thread, as specified in *note thread-id syntax::.
* If N is 'core', then R is the hexadecimal number of the core
on which the stop event was detected.
* If N is a recognized "stop reason", it describes a more
specific event that stopped the target. The currently defined
stop reasons are listed below. The AA should be '05', the
trap signal. At most one stop reason should be present.
* Otherwise, GDB should ignore this 'N:R' pair and go on to the
next; this allows us to extend the protocol in the future.
The currently defined stop reasons are:
'watch'
'rwatch'
'awatch'
The packet indicates a watchpoint hit, and R is the data
address, in hex.
'syscall_entry'
'syscall_return'
The packet indicates a syscall entry or return, and R is the
syscall number, in hex.
'library'
The packet indicates that the loaded libraries have changed.
GDB should use 'qXfer:libraries:read' to fetch a new list of
loaded libraries. The R part is ignored.
'replaylog'
The packet indicates that the target cannot continue replaying
logged execution events, because it has reached the end (or
the beginning when executing backward) of the log. The value
of R will be either 'begin' or 'end'. *Note Reverse
Execution::, for more information.
'swbreak'
The packet indicates a software breakpoint instruction was
executed, irrespective of whether it was GDB that planted the
breakpoint or the breakpoint is hardcoded in the program. The
R part must be left empty.
On some architectures, such as x86, at the architecture level,
when a breakpoint instruction executes the program counter
points at the breakpoint address plus an offset. On such
targets, the stub is responsible for adjusting the PC to point
back at the breakpoint address.
This packet should not be sent by default; older GDB versions
did not support it. GDB requests it, by supplying an
appropriate 'qSupported' feature (*note qSupported::). The
remote stub must also supply the appropriate 'qSupported'
feature indicating support.
This packet is required for correct non-stop mode operation.
'hwbreak'
The packet indicates the target stopped for a hardware
breakpoint. The R part must be left empty.
The same remarks about 'qSupported' and non-stop mode above
apply.
'fork'
The packet indicates that 'fork' was called, and R is the
thread ID of the new child process. Refer to *note thread-id
syntax:: for the format of the THREAD-ID field. This packet
is only applicable to targets that support fork events.
This packet should not be sent by default; older GDB versions
did not support it. GDB requests it, by supplying an
appropriate 'qSupported' feature (*note qSupported::). The
remote stub must also supply the appropriate 'qSupported'
feature indicating support.
'vfork'
The packet indicates that 'vfork' was called, and R is the
thread ID of the new child process. Refer to *note thread-id
syntax:: for the format of the THREAD-ID field. This packet
is only applicable to targets that support vfork events.
This packet should not be sent by default; older GDB versions
did not support it. GDB requests it, by supplying an
appropriate 'qSupported' feature (*note qSupported::). The
remote stub must also supply the appropriate 'qSupported'
feature indicating support.
'vforkdone'
The packet indicates that a child process created by a vfork
has either called 'exec' or terminated, so that the address
spaces of the parent and child process are no longer shared.
The R part is ignored. This packet is only applicable to
targets that support vforkdone events.
This packet should not be sent by default; older GDB versions
did not support it. GDB requests it, by supplying an
appropriate 'qSupported' feature (*note qSupported::). The
remote stub must also supply the appropriate 'qSupported'
feature indicating support.
'exec'
The packet indicates that 'execve' was called, and R is the
absolute pathname of the file that was executed, in hex. This
packet is only applicable to targets that support exec events.
This packet should not be sent by default; older GDB versions
did not support it. GDB requests it, by supplying an
appropriate 'qSupported' feature (*note qSupported::). The
remote stub must also supply the appropriate 'qSupported'
feature indicating support.
'create'
The packet indicates that the thread was just created. The
new thread is stopped until GDB sets it running with a
resumption packet (*note vCont packet::). This packet should
not be sent by default; GDB requests it with the *note
QThreadEvents:: packet. See also the 'w' (*note thread exit
event::) remote reply below. The R part is ignored.
'W AA'
'W AA ; process:PID'
The process exited, and AA is the exit status. This is only
applicable to certain targets.
The second form of the response, including the process ID of the
exited process, can be used only when GDB has reported support for
multiprocess protocol extensions; see *note multiprocess
extensions::. Both AA and PID are formatted as big-endian hex
strings.
'X AA'
'X AA ; process:PID'
The process terminated with signal AA.
The second form of the response, including the process ID of the
terminated process, can be used only when GDB has reported support
for multiprocess protocol extensions; see *note multiprocess
extensions::. Both AA and PID are formatted as big-endian hex
strings.
'w AA ; TID'
The thread exited, and AA is the exit status. This response should
not be sent by default; GDB requests it with the *note
QThreadEvents:: packet. See also *note thread create event::
above. AA is formatted as a big-endian hex string.
'N'
There are no resumed threads left in the target. In other words,
even though the process is alive, the last resumed thread has
exited. For example, say the target process has two threads:
thread 1 and thread 2. The client leaves thread 1 stopped, and
resumes thread 2, which subsequently exits. At this point, even
though the process is still alive, and thus no 'W' stop reply is
sent, no thread is actually executing either. The 'N' stop reply
thus informs the client that it can stop waiting for stop replies.
This packet should not be sent by default; older GDB versions did
not support it. GDB requests it, by supplying an appropriate
'qSupported' feature (*note qSupported::). The remote stub must
also supply the appropriate 'qSupported' feature indicating
support.
'O XX...'
'XX...' is hex encoding of ASCII data, to be written as the
program's console output. This can happen at any time while the
program is running and the debugger should continue to wait for
'W', 'T', etc. This reply is not permitted in non-stop mode.
'F CALL-ID,PARAMETER...'
CALL-ID is the identifier which says which host system call should
be called. This is just the name of the function. Translation
into the correct system call is only applicable as it's defined in
GDB. *Note File-I/O Remote Protocol Extension::, for a list of
implemented system calls.
'PARAMETER...' is a list of parameters as defined for this very
system call.
The target replies with this packet when it expects GDB to call a
host system call on behalf of the target. GDB replies with an
appropriate 'F' packet and keeps up waiting for the next reply
packet from the target. The latest 'C', 'c', 'S' or 's' action is
expected to be continued. *Note File-I/O Remote Protocol
Extension::, for more details.

File: gdb.info, Node: General Query Packets, Next: Architecture-Specific Protocol Details, Prev: Stop Reply Packets, Up: Remote Protocol
E.4 General Query Packets
=========================
Packets starting with 'q' are "general query packets"; packets starting
with 'Q' are "general set packets". General query and set packets are a
semi-unified form for retrieving and sending information to and from the
stub.
The initial letter of a query or set packet is followed by a name
indicating what sort of thing the packet applies to. For example, GDB
may use a 'qSymbol' packet to exchange symbol definitions with the stub.
These packet names follow some conventions:
* The name must not contain commas, colons or semicolons.
* Most GDB query and set packets have a leading upper case letter.
* The names of custom vendor packets should use a company prefix, in
lower case, followed by a period. For example, packets designed at
the Acme Corporation might begin with 'qacme.foo' (for querying
foos) or 'Qacme.bar' (for setting bars).
The name of a query or set packet should be separated from any
parameters by a ':'; the parameters themselves should be separated by
',' or ';'. Stubs must be careful to match the full packet name, and
check for a separator or the end of the packet, in case two packet names
share a common prefix. New packets should not begin with 'qC', 'qP', or
'qL'(1).
Like the descriptions of the other packets, each description here has
a template showing the packet's overall syntax, followed by an
explanation of the packet's meaning. We include spaces in some of the
templates for clarity; these are not part of the packet's syntax. No
GDB packet uses spaces to separate its components.
Here are the currently defined query and set packets:
'QAgent:1'
'QAgent:0'
Turn on or off the agent as a helper to perform some debugging
operations delegated from GDB (*note Control Agent::).
'QAllow:OP:VAL...'
Specify which operations GDB expects to request of the target, as a
semicolon-separated list of operation name and value pairs.
Possible values for OP include 'WriteReg', 'WriteMem',
'InsertBreak', 'InsertTrace', 'InsertFastTrace', and 'Stop'. VAL
is either 0, indicating that GDB will not request the operation, or
1, indicating that it may. (The target can then use this to set up
its own internals optimally, for instance if the debugger never
expects to insert breakpoints, it may not need to install its own
trap handler.)
'qC'
Return the current thread ID.
Reply:
'QC THREAD-ID'
Where THREAD-ID is a thread ID as documented in *note
thread-id syntax::.
'(anything else)'
Any other reply implies the old thread ID.
'qCRC:ADDR,LENGTH'
Compute the CRC checksum of a block of memory using CRC-32 defined
in IEEE 802.3. The CRC is computed byte at a time, taking the most
significant bit of each byte first. The initial pattern code
'0xffffffff' is used to ensure leading zeros affect the CRC.
_Note:_ This is the same CRC used in validating separate debug
files (*note Debugging Information in Separate Files: Separate
Debug Files.). However the algorithm is slightly different. When
validating separate debug files, the CRC is computed taking the
_least_ significant bit of each byte first, and the final result is
inverted to detect trailing zeros.
Reply:
'E NN'
An error (such as memory fault)
'C CRC32'
The specified memory region's checksum is CRC32.
'QDisableRandomization:VALUE'
Some target operating systems will randomize the virtual address
space of the inferior process as a security feature, but provide a
feature to disable such randomization, e.g. to allow for a more
deterministic debugging experience. On such systems, this packet
with a VALUE of 1 directs the target to disable address space
randomization for processes subsequently started via 'vRun'
packets, while a packet with a VALUE of 0 tells the target to
enable address space randomization.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. The error number NN is given as hex
digits.
''
An empty reply indicates that 'QDisableRandomization' is not
supported by the stub.
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::). This should only be done on targets that actually
support disabling address space randomization.
'QStartupWithShell:VALUE'
On UNIX-like targets, it is possible to start the inferior using a
shell program. This is the default behavior on both GDB and
'gdbserver' (*note set startup-with-shell::). This packet is used
to inform 'gdbserver' whether it should start the inferior using a
shell or not.
If VALUE is '0', 'gdbserver' will not use a shell to start the
inferior. If VALUE is '1', 'gdbserver' will use a shell to start
the inferior. All other values are considered an error.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. The error number NN is given as hex
digits.
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::). This should only be done on targets that actually
support starting the inferior using a shell.
Use of this packet is controlled by the 'set startup-with-shell'
command; *note set startup-with-shell::.
'QEnvironmentHexEncoded:HEX-VALUE'
On UNIX-like targets, it is possible to set environment variables
that will be passed to the inferior during the startup process.
This packet is used to inform 'gdbserver' of an environment
variable that has been defined by the user on GDB (*note set
environment::).
The packet is composed by HEX-VALUE, an hex encoded representation
of the NAME=VALUE format representing an environment variable. The
name of the environment variable is represented by NAME, and the
value to be assigned to the environment variable is represented by
VALUE. If the variable has no value (i.e., the value is 'null'),
then VALUE will not be present.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'OK'
The request succeeded.
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::). This should only be done on targets that actually
support passing environment variables to the starting inferior.
This packet is related to the 'set environment' command; *note set
environment::.
'QEnvironmentUnset:HEX-VALUE'
On UNIX-like targets, it is possible to unset environment variables
before starting the inferior in the remote target. This packet is
used to inform 'gdbserver' of an environment variable that has been
unset by the user on GDB (*note unset environment::).
The packet is composed by HEX-VALUE, an hex encoded representation
of the name of the environment variable to be unset.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'OK'
The request succeeded.
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::). This should only be done on targets that actually
support passing environment variables to the starting inferior.
This packet is related to the 'unset environment' command; *note
unset environment::.
'QEnvironmentReset'
On UNIX-like targets, this packet is used to reset the state of
environment variables in the remote target before starting the
inferior. In this context, reset means unsetting all environment
variables that were previously set by the user (i.e., were not
initially present in the environment). It is sent to 'gdbserver'
before the 'QEnvironmentHexEncoded' (*note
QEnvironmentHexEncoded::) and the 'QEnvironmentUnset' (*note
QEnvironmentUnset::) packets.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'OK'
The request succeeded.
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::). This should only be done on targets that actually
support passing environment variables to the starting inferior.
'QSetWorkingDir:[DIRECTORY]'
This packet is used to inform the remote server of the intended
current working directory for programs that are going to be
executed.
The packet is composed by DIRECTORY, an hex encoded representation
of the directory that the remote inferior will use as its current
working directory. If DIRECTORY is an empty string, the remote
server should reset the inferior's current working directory to its
original, empty value.
This packet is only available in extended mode (*note extended
mode::).
Reply:
'OK'
The request succeeded.
'qfThreadInfo'
'qsThreadInfo'
Obtain a list of all active thread IDs from the target (OS). Since
there may be too many active threads to fit into one reply packet,
this query works iteratively: it may require more than one
query/reply sequence to obtain the entire list of threads. The
first query of the sequence will be the 'qfThreadInfo' query;
subsequent queries in the sequence will be the 'qsThreadInfo'
query.
NOTE: This packet replaces the 'qL' query (see below).
Reply:
'm THREAD-ID'
A single thread ID
'm THREAD-ID,THREAD-ID...'
a comma-separated list of thread IDs
'l'
(lower case letter 'L') denotes end of list.
In response to each query, the target will reply with a list of one
or more thread IDs, separated by commas. GDB will respond to each
reply with a request for more thread ids (using the 'qs' form of
the query), until the target responds with 'l' (lower-case ell, for
"last"). Refer to *note thread-id syntax::, for the format of the
THREAD-ID fields.
_Note: GDB will send the 'qfThreadInfo' query during the initial
connection with the remote target, and the very first thread ID
mentioned in the reply will be stopped by GDB in a subsequent
message. Therefore, the stub should ensure that the first thread
ID in the 'qfThreadInfo' reply is suitable for being stopped by
GDB._
'qGetTLSAddr:THREAD-ID,OFFSET,LM'
Fetch the address associated with thread local storage specified by
THREAD-ID, OFFSET, and LM.
THREAD-ID is the thread ID associated with the thread for which to
fetch the TLS address. *Note thread-id syntax::.
OFFSET is the (big endian, hex encoded) offset associated with the
thread local variable. (This offset is obtained from the debug
information associated with the variable.)
LM is the (big endian, hex encoded) OS/ABI-specific encoding of the
load module associated with the thread local storage. For example,
a GNU/Linux system will pass the link map address of the shared
object associated with the thread local storage under
consideration. Other operating environments may choose to
represent the load module differently, so the precise meaning of
this parameter will vary.
Reply:
'XX...'
Hex encoded (big endian) bytes representing the address of the
thread local storage requested.
'E NN'
An error occurred. The error number NN is given as hex
digits.
''
An empty reply indicates that 'qGetTLSAddr' is not supported
by the stub.
'qGetTIBAddr:THREAD-ID'
Fetch address of the Windows OS specific Thread Information Block.
THREAD-ID is the thread ID associated with the thread.
Reply:
'XX...'
Hex encoded (big endian) bytes representing the linear address
of the thread information block.
'E NN'
An error occured. This means that either the thread was not
found, or the address could not be retrieved.
''
An empty reply indicates that 'qGetTIBAddr' is not supported
by the stub.
'qL STARTFLAG THREADCOUNT NEXTTHREAD'
Obtain thread information from RTOS. Where: STARTFLAG (one hex
digit) is one to indicate the first query and zero to indicate a
subsequent query; THREADCOUNT (two hex digits) is the maximum
number of threads the response packet can contain; and NEXTTHREAD
(eight hex digits), for subsequent queries (STARTFLAG is zero), is
returned in the response as ARGTHREAD.
Don't use this packet; use the 'qfThreadInfo' query instead (see
above).
Reply:
'qM COUNT DONE ARGTHREAD THREAD...'
Where: COUNT (two hex digits) is the number of threads being
returned; DONE (one hex digit) is zero to indicate more
threads and one indicates no further threads; ARGTHREADID
(eight hex digits) is NEXTTHREAD from the request packet;
THREAD... is a sequence of thread IDs, THREADID (eight hex
digits), from the target. See
'remote.c:parse_threadlist_response()'.
'qOffsets'
Get section offsets that the target used when relocating the
downloaded image.
Reply:
'Text=XXX;Data=YYY[;Bss=ZZZ]'
Relocate the 'Text' section by XXX from its original address.
Relocate the 'Data' section by YYY from its original address.
If the object file format provides segment information (e.g.
ELF 'PT_LOAD' program headers), GDB will relocate entire
segments by the supplied offsets.
_Note: while a 'Bss' offset may be included in the response,
GDB ignores this and instead applies the 'Data' offset to the
'Bss' section._
'TextSeg=XXX[;DataSeg=YYY]'
Relocate the first segment of the object file, which
conventionally contains program code, to a starting address of
XXX. If 'DataSeg' is specified, relocate the second segment,
which conventionally contains modifiable data, to a starting
address of YYY. GDB will report an error if the object file
does not contain segment information, or does not contain at
least as many segments as mentioned in the reply. Extra
segments are kept at fixed offsets relative to the last
relocated segment.
'qP MODE THREAD-ID'
Returns information on THREAD-ID. Where: MODE is a hex encoded 32
bit mode; THREAD-ID is a thread ID (*note thread-id syntax::).
Don't use this packet; use the 'qThreadExtraInfo' query instead
(see below).
Reply: see 'remote.c:remote_unpack_thread_info_response()'.
'QNonStop:1'
'QNonStop:0'
Enter non-stop ('QNonStop:1') or all-stop ('QNonStop:0') mode.
*Note Remote Non-Stop::, for more information.
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. The error number NN is given as hex
digits.
''
An empty reply indicates that 'QNonStop' is not supported by
the stub.
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::). Use of this packet is controlled by the 'set
non-stop' command; *note Non-Stop Mode::.
'QCatchSyscalls:1 [;SYSNO]...'
'QCatchSyscalls:0'
Enable ('QCatchSyscalls:1') or disable ('QCatchSyscalls:0')
catching syscalls from the inferior process.
For 'QCatchSyscalls:1', each listed syscall SYSNO (encoded in hex)
should be reported to GDB. If no syscall SYSNO is listed, every
system call should be reported.
Note that if a syscall not in the list is reported, GDB will still
filter the event according to its own list from all corresponding
'catch syscall' commands. However, it is more efficient to only
report the requested syscalls.
Multiple 'QCatchSyscalls:1' packets do not combine; any earlier
'QCatchSyscalls:1' list is completely replaced by the new list.
If the inferior process execs, the state of 'QCatchSyscalls' is
kept for the new process too. On targets where exec may affect
syscall numbers, for example with exec between 32 and 64-bit
processes, the client should send a new packet with the new syscall
list.
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. NN are hex digits.
''
An empty reply indicates that 'QCatchSyscalls' is not
supported by the stub.
Use of this packet is controlled by the 'set remote catch-syscalls'
command (*note set remote catch-syscalls: Remote Configuration.).
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::).
'QPassSignals: SIGNAL [;SIGNAL]...'
Each listed SIGNAL should be passed directly to the inferior
process. Signals are numbered identically to continue packets and
stop replies (*note Stop Reply Packets::). Each SIGNAL list item
should be strictly greater than the previous item. These signals
do not need to stop the inferior, or be reported to GDB. All other
signals should be reported to GDB. Multiple 'QPassSignals' packets
do not combine; any earlier 'QPassSignals' list is completely
replaced by the new list. This packet improves performance when
using 'handle SIGNAL nostop noprint pass'.
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. The error number NN is given as hex
digits.
''
An empty reply indicates that 'QPassSignals' is not supported
by the stub.
Use of this packet is controlled by the 'set remote pass-signals'
command (*note set remote pass-signals: Remote Configuration.).
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (*note
qSupported::).
'QProgramSignals: SIGNAL [;SIGNAL]...'
Each listed SIGNAL may be delivered to the inferior process.
Others should be silently discarded.
In some cases, the remote stub may need to decide whether to
deliver a signal to the program or not without GDB involvement.
One example of that is while detaching -- the program's threads may
have stopped for signals that haven't yet had a chance of being
reported to GDB, and so the remote stub can use the signal list
specified by this packet to know whether to deliver or ignore those
pending signals.
This does not influence whether to deliver a signal as requested by
a resumption packet (*note vCont packet::).
Signals are numbered identically to continue packets and stop
replies (*note Stop Reply Packets::). Each SIGNAL list item should
be strictly greater than the previous item. Multiple
'QProgramSignals' packets do not combine; any earlier
'QProgramSignals' list is completely replaced by the new list.
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. The error number NN is given as hex
digits.
''
An empty reply indicates that 'QProgramSignals' is not
supported by the stub.
Use of this packet is controlled by the 'set remote
program-signals' command (*note set remote program-signals: Remote
Configuration.). This packet is not probed by default; the remote
stub must request it, by supplying an appropriate 'qSupported'
response (*note qSupported::).
'QThreadEvents:1'
'QThreadEvents:0'
Enable ('QThreadEvents:1') or disable ('QThreadEvents:0') reporting
of thread create and exit events. *Note thread create event::, for
the reply specifications. For example, this is used in non-stop
mode when GDB stops a set of threads and synchronously waits for
the their corresponding stop replies. Without exit events, if one
of the threads exits, GDB would hang forever not knowing that it
should no longer expect a stop for that same thread. GDB does not
enable this feature unless the stub reports that it supports it by
including 'QThreadEvents+' in its 'qSupported' reply.
Reply:
'OK'
The request succeeded.
'E NN'
An error occurred. The error number NN is given as hex
digits.
''
An empty reply indicates that 'QThreadEvents' is not supported
by the stub.
Use of this packet is controlled by the 'set remote thread-events'
command (*note set remote thread-events: Remote Configuration.).
'qRcmd,COMMAND'
COMMAND (hex encoded) is passed to the local interpreter for
execution. Invalid commands should be reported using the output
string. Before the final result packet, the target may also
respond with a number of intermediate 'OOUTPUT' console output
packets. _Implementors should note that providing access to a
stubs's interpreter may have security implications_.
Reply:
'OK'
A command response with no output.
'OUTPUT'
A command response with the hex encoded output string OUTPUT.
'E NN'
Indicate a badly formed request.
''
An empty reply indicates that 'qRcmd' is not recognized.
(Note that the 'qRcmd' packet's name is separated from the command
by a ',', not a ':', contrary to the naming conventions above.
Please don't use this packet as a model for new packets.)
'qSearch:memory:ADDRESS;LENGTH;SEARCH-PATTERN'
Search LENGTH bytes at ADDRESS for SEARCH-PATTERN. Both ADDRESS
and LENGTH are encoded in hex; SEARCH-PATTERN is a sequence of
bytes, also hex encoded.
Reply:
'0'
The pattern was not found.
'1,address'
The pattern was found at ADDRESS.
'E NN'
A badly formed request or an error was encountered while
searching memory.
''
An empty reply indicates that 'qSearch:memory' is not
recognized.
'QStartNoAckMode'
Request that the remote stub disable the normal '+'/'-' protocol
acknowledgments (*note Packet Acknowledgment::).
Reply:
'OK'
The stub has switched to no-acknowledgment mode. GDB
acknowledges this response, but neither the stub nor GDB shall
send or expect further '+'/'-' acknowledgments in the current
connection.
''
An empty reply indicates that the stub does not support
no-acknowledgment mode.
'qSupported [:GDBFEATURE [;GDBFEATURE]... ]'
Tell the remote stub about features supported by GDB, and query the
stub for features it supports. This packet allows GDB and the
remote stub to take advantage of each others' features.
'qSupported' also consolidates multiple feature probes at startup,
to improve GDB performance--a single larger packet performs better
than multiple smaller probe packets on high-latency links. Some
features may enable behavior which must not be on by default, e.g.
because it would confuse older clients or stubs. Other features
may describe packets which could be automatically probed for, but
are not. These features must be reported before GDB will use them.
This "default unsupported" behavior is not appropriate for all
packets, but it helps to keep the initial connection time under
control with new versions of GDB which support increasing numbers
of packets.
Reply:
'STUBFEATURE [;STUBFEATURE]...'
The stub supports or does not support each returned
STUBFEATURE, depending on the form of each STUBFEATURE (see
below for the possible forms).
''
An empty reply indicates that 'qSupported' is not recognized,
or that no features needed to be reported to GDB.
The allowed forms for each feature (either a GDBFEATURE in the
'qSupported' packet, or a STUBFEATURE in the response) are:
'NAME=VALUE'
The remote protocol feature NAME is supported, and associated
with the specified VALUE. The format of VALUE depends on the
feature, but it must not include a semicolon.
'NAME+'
The remote protocol feature NAME is supported, and does not
need an associated value.
'NAME-'
The remote protocol feature NAME is not supported.
'NAME?'
The remote protocol feature NAME may be supported, and GDB
should auto-detect support in some other way when it is
needed. This form will not be used for GDBFEATURE
notifications, but may be used for STUBFEATURE responses.
Whenever the stub receives a 'qSupported' request, the supplied set
of GDB features should override any previous request. This allows
GDB to put the stub in a known state, even if the stub had
previously been communicating with a different version of GDB.
The following values of GDBFEATURE (for the packet sent by GDB) are
defined:
'multiprocess'
This feature indicates whether GDB supports multiprocess
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'multiprocess+' in its 'qSupported' reply. *Note
multiprocess extensions::, for details.
'xmlRegisters'
This feature indicates that GDB supports the XML target
description. If the stub sees 'xmlRegisters=' with target
specific strings separated by a comma, it will report register
description.
'qRelocInsn'
This feature indicates whether GDB supports the 'qRelocInsn'
packet (*note Relocate instruction reply packet: Tracepoint
Packets.).
'swbreak'
This feature indicates whether GDB supports the swbreak stop
reason in stop replies. *Note swbreak stop reason::, for
details.
'hwbreak'
This feature indicates whether GDB supports the hwbreak stop
reason in stop replies. *Note swbreak stop reason::, for
details.
'fork-events'
This feature indicates whether GDB supports fork event
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'fork-events+' in its 'qSupported' reply.
'vfork-events'
This feature indicates whether GDB supports vfork event
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'vfork-events+' in its 'qSupported' reply.
'exec-events'
This feature indicates whether GDB supports exec event
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'exec-events+' in its 'qSupported' reply.
'vContSupported'
This feature indicates whether GDB wants to know the supported
actions in the reply to 'vCont?' packet.
Stubs should ignore any unknown values for GDBFEATURE. Any GDB
which sends a 'qSupported' packet supports receiving packets of
unlimited length (earlier versions of GDB may reject overly long
responses). Additional values for GDBFEATURE may be defined in the
future to let the stub take advantage of new features in GDB, e.g.
incompatible improvements in the remote protocol--the
'multiprocess' feature is an example of such a feature. The stub's
reply should be independent of the GDBFEATURE entries sent by GDB;
first GDB describes all the features it supports, and then the stub
replies with all the features it supports.
Similarly, GDB will silently ignore unrecognized stub feature
responses, as long as each response uses one of the standard forms.
Some features are flags. A stub which supports a flag feature
should respond with a '+' form response. Other features require
values, and the stub should respond with an '=' form response.
Each feature has a default value, which GDB will use if
'qSupported' is not available or if the feature is not mentioned in
the 'qSupported' response. The default values are fixed; a stub is
free to omit any feature responses that match the defaults.
Not all features can be probed, but for those which can, the
probing mechanism is useful: in some cases, a stub's internal
architecture may not allow the protocol layer to know some
information about the underlying target in advance. This is
especially common in stubs which may be configured for multiple
targets.
These are the currently defined stub features and their properties:
Feature Name Value Default Probe
Required Allowed
'PacketSize' Yes '-' No
'qXfer:auxv:read' No '-' Yes
'qXfer:btrace:read' No '-' Yes
'qXfer:btrace-conf:read' No '-' Yes
'qXfer:exec-file:read' No '-' Yes
'qXfer:features:read' No '-' Yes
'qXfer:libraries:read' No '-' Yes
'qXfer:libraries-svr4:read'No '-' Yes
'augmented-libraries-svr4-read'No '-' No
'qXfer:memory-map:read' No '-' Yes
'qXfer:sdata:read' No '-' Yes
'qXfer:siginfo:read' No '-' Yes
'qXfer:siginfo:write' No '-' Yes
'qXfer:threads:read' No '-' Yes
'qXfer:traceframe-info:read'No '-' Yes
'qXfer:uib:read' No '-' Yes
'qXfer:fdpic:read' No '-' Yes
'Qbtrace:off' Yes '-' Yes
'Qbtrace:bts' Yes '-' Yes
'Qbtrace:pt' Yes '-' Yes
'Qbtrace-conf:bts:size' Yes '-' Yes
'Qbtrace-conf:pt:size' Yes '-' Yes
'QNonStop' No '-' Yes
'QCatchSyscalls' No '-' Yes
'QPassSignals' No '-' Yes
'QStartNoAckMode' No '-' Yes
'multiprocess' No '-' No
'ConditionalBreakpoints' No '-' No
'ConditionalTracepoints' No '-' No
'ReverseContinue' No '-' No
'ReverseStep' No '-' No
'TracepointSource' No '-' No
'QAgent' No '-' No
'QAllow' No '-' No
'QDisableRandomization' No '-' No
'EnableDisableTracepoints'No '-' No
'QTBuffer:size' No '-' No
'tracenz' No '-' No
'BreakpointCommands' No '-' No
'swbreak' No '-' No
'hwbreak' No '-' No
'fork-events' No '-' No
'vfork-events' No '-' No
'exec-events' No '-' No
'QThreadEvents' No '-' No
'no-resumed' No '-' No
These are the currently defined stub features, in more detail:
'PacketSize=BYTES'
The remote stub can accept packets up to at least BYTES in
length. GDB will send packets up to this size for bulk
transfers, and will never send larger packets. This is a
limit on the data characters in the packet, including the
frame and checksum. There is no trailing NUL byte in a remote
protocol packet; if the stub stores packets in a
NUL-terminated format, it should allow an extra byte in its
buffer for the NUL. If this stub feature is not supported, GDB
guesses based on the size of the 'g' packet response.
'qXfer:auxv:read'
The remote stub understands the 'qXfer:auxv:read' packet
(*note qXfer auxiliary vector read::).
'qXfer:btrace:read'
The remote stub understands the 'qXfer:btrace:read' packet
(*note qXfer btrace read::).
'qXfer:btrace-conf:read'
The remote stub understands the 'qXfer:btrace-conf:read'
packet (*note qXfer btrace-conf read::).
'qXfer:exec-file:read'
The remote stub understands the 'qXfer:exec-file:read' packet
(*note qXfer executable filename read::).
'qXfer:features:read'
The remote stub understands the 'qXfer:features:read' packet
(*note qXfer target description read::).
'qXfer:libraries:read'
The remote stub understands the 'qXfer:libraries:read' packet
(*note qXfer library list read::).
'qXfer:libraries-svr4:read'
The remote stub understands the 'qXfer:libraries-svr4:read'
packet (*note qXfer svr4 library list read::).
'augmented-libraries-svr4-read'
The remote stub understands the augmented form of the
'qXfer:libraries-svr4:read' packet (*note qXfer svr4 library
list read::).
'qXfer:memory-map:read'
The remote stub understands the 'qXfer:memory-map:read' packet
(*note qXfer memory map read::).
'qXfer:sdata:read'
The remote stub understands the 'qXfer:sdata:read' packet
(*note qXfer sdata read::).
'qXfer:siginfo:read'
The remote stub understands the 'qXfer:siginfo:read' packet
(*note qXfer siginfo read::).
'qXfer:siginfo:write'
The remote stub understands the 'qXfer:siginfo:write' packet
(*note qXfer siginfo write::).
'qXfer:threads:read'
The remote stub understands the 'qXfer:threads:read' packet
(*note qXfer threads read::).
'qXfer:traceframe-info:read'
The remote stub understands the 'qXfer:traceframe-info:read'
packet (*note qXfer traceframe info read::).
'qXfer:uib:read'
The remote stub understands the 'qXfer:uib:read' packet (*note
qXfer unwind info block::).
'qXfer:fdpic:read'
The remote stub understands the 'qXfer:fdpic:read' packet
(*note qXfer fdpic loadmap read::).
'QNonStop'
The remote stub understands the 'QNonStop' packet (*note
QNonStop::).
'QCatchSyscalls'
The remote stub understands the 'QCatchSyscalls' packet (*note
QCatchSyscalls::).
'QPassSignals'
The remote stub understands the 'QPassSignals' packet (*note
QPassSignals::).
'QStartNoAckMode'
The remote stub understands the 'QStartNoAckMode' packet and
prefers to operate in no-acknowledgment mode. *Note Packet
Acknowledgment::.
'multiprocess'
The remote stub understands the multiprocess extensions to the
remote protocol syntax. The multiprocess extensions affect
the syntax of thread IDs in both packets and replies (*note
thread-id syntax::), and add process IDs to the 'D' packet and
'W' and 'X' replies. Note that reporting this feature
indicates support for the syntactic extensions only, not that
the stub necessarily supports debugging of more than one
process at a time. The stub must not use multiprocess
extensions in packet replies unless GDB has also indicated it
supports them in its 'qSupported' request.
'qXfer:osdata:read'
The remote stub understands the 'qXfer:osdata:read' packet
((*note qXfer osdata read::).
'ConditionalBreakpoints'
The target accepts and implements evaluation of conditional
expressions defined for breakpoints. The target will only
report breakpoint triggers when such conditions are true
(*note Break Conditions: Conditions.).
'ConditionalTracepoints'
The remote stub accepts and implements conditional expressions
defined for tracepoints (*note Tracepoint Conditions::).
'ReverseContinue'
The remote stub accepts and implements the reverse continue
packet (*note bc::).
'ReverseStep'
The remote stub accepts and implements the reverse step packet
(*note bs::).
'TracepointSource'
The remote stub understands the 'QTDPsrc' packet that supplies
the source form of tracepoint definitions.
'QAgent'
The remote stub understands the 'QAgent' packet.
'QAllow'
The remote stub understands the 'QAllow' packet.
'QDisableRandomization'
The remote stub understands the 'QDisableRandomization'
packet.
'StaticTracepoint'
The remote stub supports static tracepoints.
'InstallInTrace'
The remote stub supports installing tracepoint in tracing.
'EnableDisableTracepoints'
The remote stub supports the 'QTEnable' (*note QTEnable::) and
'QTDisable' (*note QTDisable::) packets that allow tracepoints
to be enabled and disabled while a trace experiment is
running.
'QTBuffer:size'
The remote stub supports the 'QTBuffer:size' (*note
QTBuffer-size::) packet that allows to change the size of the
trace buffer.
'tracenz'
The remote stub supports the 'tracenz' bytecode for collecting
strings. See *note Bytecode Descriptions:: for details about
the bytecode.
'BreakpointCommands'
The remote stub supports running a breakpoint's command list
itself, rather than reporting the hit to GDB.
'Qbtrace:off'
The remote stub understands the 'Qbtrace:off' packet.
'Qbtrace:bts'
The remote stub understands the 'Qbtrace:bts' packet.
'Qbtrace:pt'
The remote stub understands the 'Qbtrace:pt' packet.
'Qbtrace-conf:bts:size'
The remote stub understands the 'Qbtrace-conf:bts:size'
packet.
'Qbtrace-conf:pt:size'
The remote stub understands the 'Qbtrace-conf:pt:size' packet.
'swbreak'
The remote stub reports the 'swbreak' stop reason for memory
breakpoints.
'hwbreak'
The remote stub reports the 'hwbreak' stop reason for hardware
breakpoints.
'fork-events'
The remote stub reports the 'fork' stop reason for fork
events.
'vfork-events'
The remote stub reports the 'vfork' stop reason for vfork
events and vforkdone events.
'exec-events'
The remote stub reports the 'exec' stop reason for exec
events.
'vContSupported'
The remote stub reports the supported actions in the reply to
'vCont?' packet.
'QThreadEvents'
The remote stub understands the 'QThreadEvents' packet.
'no-resumed'
The remote stub reports the 'N' stop reply.
'qSymbol::'
Notify the target that GDB is prepared to serve symbol lookup
requests. Accept requests from the target for the values of
symbols.
Reply:
'OK'
The target does not need to look up any (more) symbols.
'qSymbol:SYM_NAME'
The target requests the value of symbol SYM_NAME (hex
encoded). GDB may provide the value by using the
'qSymbol:SYM_VALUE:SYM_NAME' message, described below.
'qSymbol:SYM_VALUE:SYM_NAME'
Set the value of SYM_NAME to SYM_VALUE.
SYM_NAME (hex encoded) is the name of a symbol whose value the
target has previously requested.
SYM_VALUE (hex) is the value for symbol SYM_NAME. If GDB cannot
supply a value for SYM_NAME, then this field will be empty.
Reply:
'OK'
The target does not need to look up any (more) symbols.
'qSymbol:SYM_NAME'
The target requests the value of a new symbol SYM_NAME (hex
encoded). GDB will continue to supply the values of symbols
(if available), until the target ceases to request them.
'qTBuffer'
'QTBuffer'
'QTDisconnected'
'QTDP'
'QTDPsrc'
'QTDV'
'qTfP'
'qTfV'
'QTFrame'
'qTMinFTPILen'
*Note Tracepoint Packets::.
'qThreadExtraInfo,THREAD-ID'
Obtain from the target OS a printable string description of thread
attributes for the thread THREAD-ID; see *note thread-id syntax::,
for the forms of THREAD-ID. This string may contain anything that
the target OS thinks is interesting for GDB to tell the user about
the thread. The string is displayed in GDB's 'info threads'
display. Some examples of possible thread extra info strings are
'Runnable', or 'Blocked on Mutex'.
Reply:
'XX...'
Where 'XX...' is a hex encoding of ASCII data, comprising the
printable string containing the extra information about the
thread's attributes.
(Note that the 'qThreadExtraInfo' packet's name is separated from
the command by a ',', not a ':', contrary to the naming conventions
above. Please don't use this packet as a model for new packets.)
'QTNotes'
'qTP'
'QTSave'
'qTsP'
'qTsV'
'QTStart'
'QTStop'
'QTEnable'
'QTDisable'
'QTinit'
'QTro'
'qTStatus'
'qTV'
'qTfSTM'
'qTsSTM'
'qTSTMat'
*Note Tracepoint Packets::.
'qXfer:OBJECT:read:ANNEX:OFFSET,LENGTH'
Read uninterpreted bytes from the target's special data area
identified by the keyword OBJECT. Request LENGTH bytes starting at
OFFSET bytes into the data. The content and encoding of ANNEX is
specific to OBJECT; it can supply additional details about what
data to access.
Reply:
'm DATA'
Data DATA (*note Binary Data::) has been read from the target.
There may be more data at a higher address (although it is
permitted to return 'm' even for the last valid block of data,
as long as at least one byte of data was read). It is
possible for DATA to have fewer bytes than the LENGTH in the
request.
'l DATA'
Data DATA (*note Binary Data::) has been read from the target.
There is no more data to be read. It is possible for DATA to
have fewer bytes than the LENGTH in the request.
'l'
The OFFSET in the request is at the end of the data. There is
no more data to be read.
'E00'
The request was malformed, or ANNEX was invalid.
'E NN'
The offset was invalid, or there was an error encountered
reading the data. The NN part is a hex-encoded 'errno' value.
''
An empty reply indicates the OBJECT string was not recognized
by the stub, or that the object does not support reading.
Here are the specific requests of this form defined so far. All
the 'qXfer:OBJECT:read:...' requests use the same reply formats,
listed above.
'qXfer:auxv:read::OFFSET,LENGTH'
Access the target's "auxiliary vector". *Note auxiliary
vector: OS Information. Note ANNEX must be empty.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:btrace:read:ANNEX:OFFSET,LENGTH'
Return a description of the current branch trace. *Note
Branch Trace Format::. The annex part of the generic 'qXfer'
packet may have one of the following values:
'all'
Returns all available branch trace.
'new'
Returns all available branch trace if the branch trace
changed since the last read request.
'delta'
Returns the new branch trace since the last read request.
Adds a new block to the end of the trace that begins at
zero and ends at the source location of the first branch
in the trace buffer. This extra block is used to stitch
traces together.
If the trace buffer overflowed, returns an error
indicating the overflow.
This packet is not probed by default; the remote stub must
request it by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:btrace-conf:read::OFFSET,LENGTH'
Return a description of the current branch trace
configuration. *Note Branch Trace Configuration Format::.
This packet is not probed by default; the remote stub must
request it by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:exec-file:read:ANNEX:OFFSET,LENGTH'
Return the full absolute name of the file that was executed to
create a process running on the remote system. The annex
specifies the numeric process ID of the process to query,
encoded as a hexadecimal number. If the annex part is empty
the remote stub should return the filename corresponding to
the currently executing process.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:features:read:ANNEX:OFFSET,LENGTH'
Access the "target description". *Note Target Descriptions::.
The annex specifies which XML document to access. The main
description is always loaded from the 'target.xml' annex.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:libraries:read:ANNEX:OFFSET,LENGTH'
Access the target's list of loaded libraries. *Note Library
List Format::. The annex part of the generic 'qXfer' packet
must be empty (*note qXfer read::).
Targets which maintain a list of libraries in the program's
memory do not need to implement this packet; it is designed
for platforms where the operating system manages the list of
loaded libraries.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:libraries-svr4:read:ANNEX:OFFSET,LENGTH'
Access the target's list of loaded libraries when the target
is an SVR4 platform. *Note Library List Format for SVR4
Targets::. The annex part of the generic 'qXfer' packet must
be empty unless the remote stub indicated it supports the
augmented form of this packet by supplying an appropriate
'qSupported' response (*note qXfer read::, *note
qSupported::).
This packet is optional for better performance on SVR4
targets. GDB uses memory read packets to read the SVR4
library list otherwise.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
If the remote stub indicates it supports the augmented form of
this packet then the annex part of the generic 'qXfer' packet
may contain a semicolon-separated list of 'NAME=VALUE'
arguments. The currently supported arguments are:
'start=ADDRESS'
A hexadecimal number specifying the address of the
'struct link_map' to start reading the library list from.
If unset or zero then the first 'struct link_map' in the
library list will be chosen as the starting point.
'prev=ADDRESS'
A hexadecimal number specifying the address of the
'struct link_map' immediately preceding the 'struct
link_map' specified by the 'start' argument. If unset or
zero then the remote stub will expect that no 'struct
link_map' exists prior to the starting point.
Arguments that are not understood by the remote stub will be
silently ignored.
'qXfer:memory-map:read::OFFSET,LENGTH'
Access the target's "memory-map". *Note Memory Map Format::.
The annex part of the generic 'qXfer' packet must be empty
(*note qXfer read::).
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:sdata:read::OFFSET,LENGTH'
Read contents of the extra collected static tracepoint marker
information. The annex part of the generic 'qXfer' packet
must be empty (*note qXfer read::). *Note Tracepoint Action
Lists: Tracepoint Actions.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:siginfo:read::OFFSET,LENGTH'
Read contents of the extra signal information on the target
system. The annex part of the generic 'qXfer' packet must be
empty (*note qXfer read::).
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:threads:read::OFFSET,LENGTH'
Access the list of threads on target. *Note Thread List
Format::. The annex part of the generic 'qXfer' packet must
be empty (*note qXfer read::).
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:traceframe-info:read::OFFSET,LENGTH'
Return a description of the current traceframe's contents.
*Note Traceframe Info Format::. The annex part of the generic
'qXfer' packet must be empty (*note qXfer read::).
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:uib:read:PC:OFFSET,LENGTH'
Return the unwind information block for PC. This packet is
used on OpenVMS/ia64 to ask the kernel unwind information.
This packet is not probed by default.
'qXfer:fdpic:read:ANNEX:OFFSET,LENGTH'
Read contents of 'loadmap's on the target system. The annex,
either 'exec' or 'interp', specifies which 'loadmap',
executable 'loadmap' or interpreter 'loadmap' to read.
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:osdata:read::OFFSET,LENGTH'
Access the target's "operating system information". *Note
Operating System Information::.
'qXfer:OBJECT:write:ANNEX:OFFSET:DATA...'
Write uninterpreted bytes into the target's special data area
identified by the keyword OBJECT, starting at OFFSET bytes into the
data. The binary-encoded data (*note Binary Data::) to be written
is given by DATA.... The content and encoding of ANNEX is specific
to OBJECT; it can supply additional details about what data to
access.
Reply:
'NN'
NN (hex encoded) is the number of bytes written. This may be
fewer bytes than supplied in the request.
'E00'
The request was malformed, or ANNEX was invalid.
'E NN'
The offset was invalid, or there was an error encountered
writing the data. The NN part is a hex-encoded 'errno' value.
''
An empty reply indicates the OBJECT string was not recognized
by the stub, or that the object does not support writing.
Here are the specific requests of this form defined so far. All
the 'qXfer:OBJECT:write:...' requests use the same reply formats,
listed above.
'qXfer:siginfo:write::OFFSET:DATA...'
Write DATA to the extra signal information on the target
system. The annex part of the generic 'qXfer' packet must be
empty (*note qXfer write::).
This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(*note qSupported::).
'qXfer:OBJECT:OPERATION:...'
Requests of this form may be added in the future. When a stub does
not recognize the OBJECT keyword, or its support for OBJECT does
not recognize the OPERATION keyword, the stub must respond with an
empty packet.
'qAttached:PID'
Return an indication of whether the remote server attached to an
existing process or created a new process. When the multiprocess
protocol extensions are supported (*note multiprocess
extensions::), PID is an integer in hexadecimal format identifying
the target process. Otherwise, GDB will omit the PID field and the
query packet will be simplified as 'qAttached'.
This query is used, for example, to know whether the remote process
should be detached or killed when a GDB session is ended with the
'quit' command.
Reply:
'1'
The remote server attached to an existing process.
'0'
The remote server created a new process.
'E NN'
A badly formed request or an error was encountered.
'Qbtrace:bts'
Enable branch tracing for the current thread using Branch Trace
Store.
Reply:
'OK'
Branch tracing has been enabled.
'E.errtext'
A badly formed request or an error was encountered.
'Qbtrace:pt'
Enable branch tracing for the current thread using Intel Processor
Trace.
Reply:
'OK'
Branch tracing has been enabled.
'E.errtext'
A badly formed request or an error was encountered.
'Qbtrace:off'
Disable branch tracing for the current thread.
Reply:
'OK'
Branch tracing has been disabled.
'E.errtext'
A badly formed request or an error was encountered.
'Qbtrace-conf:bts:size=VALUE'
Set the requested ring buffer size for new threads that use the
btrace recording method in bts format.
Reply:
'OK'
The ring buffer size has been set.
'E.errtext'
A badly formed request or an error was encountered.
'Qbtrace-conf:pt:size=VALUE'
Set the requested ring buffer size for new threads that use the
btrace recording method in pt format.
Reply:
'OK'
The ring buffer size has been set.
'E.errtext'
A badly formed request or an error was encountered.
---------- Footnotes ----------
(1) The 'qP' and 'qL' packets predate these conventions, and have
arguments without any terminator for the packet name; we suspect they
are in widespread use in places that are difficult to upgrade. The 'qC'
packet has no arguments, but some existing stubs (e.g. RedBoot) are
known to not check for the end of the packet.
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