sna: Record git-tree used for compilation

Hopefully, I have all the dependencies correct for auto-updating and
should continue to work with tarballs...

The next step is to perhaps include it in the usual version number,
perhaps as patch level?

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

configure.ac

@@ -59,6 +59,14 @@ m4_ifndef([XORG_DRIVER_CHECK_EXT],
 LT_PREREQ([2.2])
 LT_INIT([disable-static])
 
+# Are we in a git checkout?
+dot_git=no
+if test -e .git; then
+	AC_DEFINE(HAVE_DOT_GIT, 1, [Are we in a git checkout?])
+	dot_git=yes
+fi
+AM_CONDITIONAL(HAVE_DOT_GIT, test x$dot_git = xyes)
+
 PKG_CHECK_MODULES(GEN4ASM, [intel-gen4asm >= 1.2], [gen4asm=yes], [gen4asm=no])
 AM_CONDITIONAL(HAVE_GEN4ASM, test x$gen4asm = xyes)
 

src/sna/Makefile.am

@@ -99,3 +99,10 @@ libsna_la_SOURCES += \
 	kgem_debug_gen6.c \
 	$(NULL)
 endif
+
+if HAVE_DOT_GIT
+git_version.h: $(top_builddir)/.git/HEAD $(shell sed -e '/ref:/!d' -e 's#ref: *#$(top_builddir)/.git/#' < $(top_builddir)/.git/HEAD)
+	@echo "Recording git-tree used for compilation: `git describe`"
+	@V=`git describe`; echo "static const char git_version[] = \"$$V\";" > git_version.h
+sna_driver.c: git_version.h
+endif

src/sna/sna_driver.c

@@ -71,6 +71,10 @@ USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <sys/poll.h>
 #include "i915_drm.h"
 
+#if HAVE_DOT_GIT
+#include "git_version.h"
+#endif
+
 #if DEBUG_DRIVER
 #undef DBG
 #define DBG(x) ErrorF x
@@ -1013,6 +1017,12 @@ void sna_init_scrn(ScrnInfoPtr scrn, int entity_num)
 {
 	EntityInfoPtr entity;
 
+#if HAVE_DOT_GIT
+	xf86DrvMsg(scrn->scrnIndex, X_INFO,
+		   "SNA compiled from %s\n",
+		   git_version);
+#endif
+
 	DBG(("%s\n", __FUNCTION__));
 
 	sna_device_key = xf86AllocateEntityPrivateIndex();