kbuild: use -fmacro-prefix-map to make __FILE__ a relative path
The __FILE__ macro is used everywhere in U-Boot to locate the file
printing the log message, such as WARN_ON(), etc. If U-Boot is
built out of tree, this can be a long absolute path.
This is because Kbuild runs in the objtree instead of the srctree,
then __FILE__ is expanded to a file path prefixed with $(srctree)/.
A brand-new option from GCC, -fmacro-prefix-map, solves this problem.
If your compiler supports it, __FILE__ is the relative path from the
srctree regardless of O= option. This provides more readable log,
more reproducible builds, and smaller image size.
[ Linux commit: a73619a845d5625079cc1b3b820f44c899618388 ]
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 143644c..316944c 100644
--- a/Makefile
+++ b/Makefile
@@ -595,6 +595,9 @@
KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks)
+# change __FILE__ to the relative path from the srctree
+KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
+
KBUILD_CFLAGS += -g
# $(KBUILD_AFLAGS) sets -g, which causes gcc to pass a suitable -g<format>
# option to the assembler.