From 198ffee1cb7670b3d3ef1abde8c17d7968a682a2 Mon Sep 17 00:00:00 2001
From: Vladimir Rutsky <vladimir@rutsky.org>
Date: Mon, 1 Feb 2016 00:17:11 +0300
Subject: [PATCH] add help message to busexmp example

---
 busexmp.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/busexmp.c b/busexmp.c
index 5464902..d342a6e 100644
--- a/busexmp.c
+++ b/busexmp.c
@@ -74,7 +74,16 @@ static struct buse_operations aop = {
 
 int main(int argc, char *argv[])
 {
-  (void)(argc);
+  if (argc != 2)
+  {
+    fprintf(stderr, 
+        "Usage:\n"
+        "  %s /dev/nbd0\n"
+        "Don't forget to load nbd kernel module (`modprobe nbd`) and\n"
+        "run example from root.\n", argv[0]);
+    return 1;
+  }
+
   data = malloc(aop.size);
 
   return buse_main(argv[1], &aop, (void *)&xmpl_debug);