kbuild: gitignore output directory

When compiling into output directory using O=, many files
created under KBUILD_OUTPUT that git considers
as new ones; git clients, ex. "git gui" lists it, and it clutters
file list making it difficult to see what was really changed

Generate .gitignore in output directory that ignores all
its content

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@linux.intel.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 97ee0be24d52..d487fca342c4 100644
--- a/Makefile
+++ b/Makefile
@@ -483,10 +483,13 @@ PHONY += outputmakefile
 # outputmakefile generates a Makefile in the output directory, if using a
 # separate output directory. This allows convenient use of make in the
 # output directory.
+# At the same time when output Makefile generated, generate .gitignore to
+# ignore whole output directory
 outputmakefile:
 ifneq ($(KBUILD_SRC),)
         $(Q)ln -fsn $(srctree) source
         $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
+        $(Q){ echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
 endif
 
 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)