[PATCH] kvm tools: Add debug() helper

[Cyrill Gorcunov <gorcunov@gmail.com>]

Useful for debugging. It adds "--debug" option as well so
debug prints are seen only if user asked for them.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---

No real users in code yet, the patches with debug()
are in stage, posted out to not loose it.

Thanks.

 tools/kvm/Documentation/kvm-run.txt |    3 +++
 tools/kvm/include/kvm/util.h        |   10 ++++++++++
 tools/kvm/kvm-run.c                 |    4 ++++
 3 files changed, 17 insertions(+)

Index: linux-2.6.git/tools/kvm/Documentation/kvm-run.txt
=====================================================================
--- linux-2.6.git.orig/tools/kvm/Documentation/kvm-run.txt
+++ linux-2.6.git/tools/kvm/Documentation/kvm-run.txt
@@ -55,6 +55,9 @@ OPTIONS
 --cpus::
 	The number of virtual CPUs to run.

+--debug::
+	Enable debug messages.
+
 SEE ALSO
 --------
 linkkvm:
Index: linux-2.6.git/tools/kvm/include/kvm/util.h
=====================================================================
--- linux-2.6.git.orig/tools/kvm/include/kvm/util.h
+++ linux-2.6.git/tools/kvm/include/kvm/util.h
@@ -15,6 +15,7 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
+#include <stdbool.h>
 #include <errno.h>
 #include <limits.h>
 #include <sys/param.h>
@@ -29,6 +30,8 @@
 #endif
 #endif

+extern bool do_debug_print;
+
 extern void die(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));
 extern void die_perror(const char *s) NORETURN;
 extern int error(const char *err, ...) __attribute__((format (printf, 1, 2)));
@@ -36,6 +39,13 @@ extern void warning(const char *err, ...
 extern void info(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern void set_die_routine(void (*routine)(const char *err, va_list params) NORETURN);

+#define debug(fmt, ...)							\
+	do {								\
+		if (do_debug_print)					\
+			info("(%s) %s:%d: " fmt, __FILE__,		\
+				__func__, __LINE__, ##__VA_ARGS__);	\
+	} while (0)
+
 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))

 #define DIE_IF(cnd)						\
Index: linux-2.6.git/tools/kvm/kvm-run.c
=====================================================================
--- linux-2.6.git.orig/tools/kvm/kvm-run.c
+++ linux-2.6.git/tools/kvm/kvm-run.c
@@ -66,6 +66,8 @@ static bool virtio_rng;
 extern bool ioport_debug;
 extern int  active_console;

+bool do_debug_print = false;
+
 static int nrcpus = 1;

 static const char * const run_usage[] = {
@@ -126,6 +128,8 @@ static const struct option options[] = {
 			"Enable single stepping"),
 	OPT_BOOLEAN('g', "ioport-debug", &ioport_debug,
 			"Enable ioport debugging"),
+	OPT_BOOLEAN('\0', "debug", &do_debug_print,
+			"Enable debug messages"),
 	OPT_END()
 };