[PATCH] kbuild: automatically append a short string to the version based upon the git commit

If CONFIG_AUTO_LOCALVERSION is set, the user is using a git-based tree, and the
current HEAD is not referred to by any tags in .git/refs/tags/, append -g and
the first 8 characters of the commit to the version string.  This makes it
easier to use git-bisect, and/or to do a daily build, without trampling on your
older, working builds, or accidentally setting up conflicting sets of modules.

Signed-off-by: Ryan Anderson <ryan@michonline.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

init/Kconfig

@@ -77,6 +77,22 @@ config LOCALVERSION
 	  object and source tree, in that order.  Your total string can
 	  be a maximum of 64 characters.
 
+config LOCALVERSION_AUTO
+	bool "Automatically append version information to the version string"
+	default y
+	help
+	  This will try to automatically determine if the current tree is a
+	  release tree by looking for git tags that
+	  belong to the current top of tree revision.
+
+	  A string of the format -gxxxxxxxx will be added to the localversion
+	  if a git based tree is found.  The string generated by this will be
+	  appended after any matching localversion* files, and after the value
+	  set in CONFIG_LOCALVERSION
+
+	  Note: This requires Perl, and a git repository, but not necessarily
+	  the git or cogito tools to be installed.
+
 config SWAP
 	bool "Support for paging of anonymous memory (swap)"
 	depends on MMU