Sweden-Number/documentation/porting.sgml

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<chapter id="porting">
<title>Porting Wine to new Platforms</title>
<para>Porting Wine to different (UNIX-based) operating systems...</para>
<sect1 id="wine-porting">
<title>Porting</title>
<para>
written by ???
</para>
<para>
(Extracted from <filename>wine/documentation/how-to-port</filename>)
</para>
<sect2>
<title>What is this?</title>
<para>
This note is a short description of:
</para>
<itemizedlist>
<listitem>
<para>How to port Wine to your favorite operating system</para>
</listitem>
<listitem>
<para>Why you probably shouldn't use <symbol>#ifdef MyOS</symbol></para>
</listitem>
<listitem>
<para>What to do instead.</para>
</listitem>
</itemizedlist>
<para>
This document does not say a thing about how to port Wine to
non-386 operating systems, though. You would need a CPU
emulator. Let's get Wine into a better shape on 386 first,
OK?
</para>
</sect2>
<sect2>
<title>Why <symbol>#ifdef MyOS</symbol> is probably a mistake.</title>
<para>
Operating systems change. Maybe yours doesn't have the
<filename>foo.h</filename> header, but maybe a future
version will have it. If you want to <symbol>#include
&lt;foo.h&gt;</symbol>, it doesn't matter what operating
system you are using; it only matters whether
<filename>foo.h</filename> is there.
</para>
<para>
Furthermore, operating systems change names or "fork" into
several ones. An <symbol>#ifdef MyOs</symbol> will break
over time.
</para>
<para>
If you use the feature of <command>autoconf</command> -- the
Gnu auto-configuration utility -- wisely, you will help
future porters automatically because your changes will test
for <emphasis>features</emphasis>, not names of operating
systems. A feature can be many things:
</para>
<itemizedlist>
<listitem>
<para>existence of a header file</para>
</listitem>
<listitem>
<para>existence of a library function</para>
</listitem>
<listitem>
<para>existence of libraries</para>
</listitem>
<listitem>
<para>bugs in header files, library functions, the compiler, ...</para>
</listitem>
<listitem>
<para>(you name it)</para>
</listitem>
</itemizedlist>
<para>
You will need Gnu Autoconf, which you can get from your
friendly Gnu mirror. This program takes Wine's
<filename>configure.in</filename> file and produces a
<filename>configure</filename> shell script that users use
to configure Wine to their system.
</para>
<para>
There <emphasis>are</emphasis> exceptions to the "avoid
<symbol>#ifdef MyOS</symbol>" rule. Wine, for example, needs
the internals of the signal stack -- that cannot easily be
described in terms of features.
</para>
<para>
Let's now turn to specific porting problems and how to solve
them.
</para>
</sect2>
<sect2>
<title>MyOS doesn't have the <filename>foo.h</filename> header!</title>
<para>
This first step is to make <command>autoconf</command> check
for this header. In <filename>configure.in</filename> you
add a segment like this in the section that checks for
header files (search for "header files"):
</para>
<programlisting>
AC_CHECK_HEADER(foo.h, AC_DEFINE(HAVE_FOO_H))
</programlisting>
<para>
If your operating system supports a header file with the
same contents but a different name, say
<filename>bar.h</filename>, add a check for that also.
</para>
<para>
Now you can change
</para>
<programlisting>
#include &lt;foo.h&gt;
</programlisting>
<para>
to
</para>
<programlisting>
#ifdef HAVE_FOO_H
#include &lt;foo.h&gt;
#elif defined (HAVE_BAR_H)
#include &lt;bar.h&gt;
#endif
</programlisting>
<para>
If your system doesn't have a corresponding header file even
though it has the library functions being used, you might
have to add an <symbol>#else</symbol> section to the
conditional. Avoid this if you can.
</para>
<para>
You will also need to add <symbol>#undef HAVE_FOO_H</symbol>
(etc.) to <filename>include/config.h.in</filename>
</para>
<para>
Finish up with <command>make configure</command> and
<command>./configure</command>.
</para>
</sect2>
<sect2>
<title>MyOS doesn't have the <function>bar</function> function!</title>
<para>
A typical example of this is the
<function>memmove</function> function. To solve this
problem you would add <function>memmove</function> to the
list of functions that <command>autoconf</command> checks
for. In <filename>configure.in</filename> you search for
<function>AC_CHECK_FUNCS</function> and add
<function>memmove</function>. (You will notice that someone
already did this for this particular function.)
</para>
<para>
Secondly, you will also need to add <symbol>#undef
HAVE_BAR</symbol> to
<filename>include/config.h.in</filename>
</para>
<para>
The next step depends on the nature of the missing function.
</para>
<variablelist>
<varlistentry>
<term>Case 1:</term>
<listitem>
<para>
It's easy to write a complete implementation of the
function. (<function>memmove</function> belongs to
this case.)
</para>
<para>
You add your implementation in
<filename>misc/port.c</filename> surrounded by
<symbol>#ifndef HAVE_MEMMOVE</symbol> and
<symbol>#endif</symbol>.
</para>
<para>
You might have to add a prototype for your function.
If so, <filename>include/miscemu.h</filename> might be the place. Don't
forget to protect that definition by <symbol>#ifndef
HAVE_MEMMOVE</symbol> and <symbol>#endif</symbol> also!
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Case 2:</term>
<listitem>
<para>
A general implementation is hard, but Wine is only
using a special case.
</para>
<para>
An example is the various <function>wait</function>
calls used in <function>SIGNAL_child</function> from
<filename>loader/signal.c</filename>. Here we have a
multi-branch case on features:
</para>
<programlisting>
#ifdef HAVE_THIS
...
#elif defined (HAVE_THAT)
...
#elif defined (HAVE_SOMETHING_ELSE)
...
#endif
</programlisting>
<para>
Note that this is very different from testing on
operating systems. If a new version of your operating
systems comes out and adds a new function, this code
will magically start using it.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
Finish up with <command>make configure</command> and
<command>./configure</command>.
</para>
</sect2>
</sect1>
<sect1 id="os2-wine">
<title>Running & Compiling Wine in OS/2</title>
<para>
Written by &name-robert-pouliot; <email>&email-robert-pouliot;</email>,
January 9, 1997
</para>
<para>
(Extracted from <filename>wine/documentation/wine_os2</filename>)
</para>
<para>
If you want to help the port of Wine to OS/2, send me a
message at <email>krynos@clic.net</email> I currently don't
want beta testers. It must work before we can test it.
</para>
<para>
Here is what you need to (try to) compile Wine for OS/2:
</para>
<itemizedlist>
<listitem>
<para>EMX 0.9c (fix 2)</para>
</listitem>
<listitem>
<para>XFree86 3.2 OS/2 (with development libraries)</para>
</listitem>
<listitem>
<para>
<command>bash</command>, gnu <command>make</command>,
<command>grep</command>, <command>tar</command>,
<command>bison</command>, <command>flex</command>
</para>
</listitem>
<listitem>
<para><command>sed</command> (a working copy of)</para>
</listitem>
<listitem>
<para><command>diff</command> and <command>patch</command>
are recommended</para>
</listitem>
<listitem>
<para>Lots of disk space (about 40-50 megs after EMX and XFree installed)</para>
</listitem>
</itemizedlist>
<para>
To compile:
</para>
<screen>
<prompt>$ </prompt><userinput>sh</userinput>
<prompt>$ </prompt><userinput>tools/make_os2.sh</userinput>
<prompt>$ </prompt><userinput>make depend</userinput>
<prompt>$ </prompt><userinput>make</userinput>
<prompt>$ </prompt><userinput>emxbind wine</userinput>
</screen>
<para>
Currently:
</para>
<itemizedlist>
<listitem>
<para><command>configure</command> and <command>make depend</command> work...</para>
</listitem>
<listitem>
<para><command>make</command> compiles (with a modified
Linux <filename>mman.h</filename>), but doesn't
link.</para>
</listitem>
<listitem>
<para>signal handling is horrible... (if any)</para>
</listitem>
<listitem>
<para>EMX doesn't support <function>mmap</function> (and
related), SysV IPC and <function>stafs()</function></para>
</listitem>
<listitem>
<para>
XFree86/OS2 3.2 doesn't support
<function>XShmQueryExtension()</function> and
<function>XShmPixmapFormat()</function> due to the same
lack in EMX...
</para>
</listitem>
</itemizedlist>
<para>
What needs to be redone:
</para>
<itemizedlist>
<listitem>
<para>LDT (using <function>DosAllocSeg</function> in
<filename>memory/ldt.c</filename>) *</para>
</listitem>
<listitem>
<para>Implement <function>mmap()</function> and SysV IPC in EMX *</para>
</listitem>
<listitem>
<para>File functions, </para>
</listitem>
<listitem>
<para>I/O access (do it!),</para>
</listitem>
<listitem>
<para>Communication (modem),</para>
</listitem>
<listitem>
<para>Interrupt (if int unknown, call current RealMode one...), </para>
</listitem>
<listitem>
<para>
Verify that everything is thread safe (how does Win95/NT handle multi-thread?),
</para>
</listitem>
<listitem>
<para>
Move X functions in some files (and make a wrapper, to use PM instead latter),
</para>
</listitem>
<listitem>
<para>Return right CPU type, </para>
</listitem>
<listitem>
<para>Make winsock work</para>
</listitem>
</itemizedlist>
<para>
The good things:
</para>
<itemizedlist>
<listitem>
<para>OS/2 have DOS interrupts</para>
</listitem>
<listitem>
<para>OS/2 have I/O port access</para>
</listitem>
<listitem>
<para>OS/2 have multi-thread</para>
</listitem>
<listitem>
<para>Merlin have Open32 (to be used later...)</para>
</listitem>
</itemizedlist>
</sect1>
</chapter>
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