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author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2019-08-08 01:48:08 +0900 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2019-08-12 09:01:09 +0200 |
commit | ddba08c1d702f1933f9de4ed61467140af849912 (patch) | |
tree | dbc8ab37ed6a313b51a2ec996946f613f9c3709f | |
parent | 4bbc3bb207354d819c940298133a950d7f02ea46 (diff) | |
download | barebox-ddba08c1d702f1933f9de4ed61467140af849912.tar.gz barebox-ddba08c1d702f1933f9de4ed61467140af849912.tar.xz |
kbuild: use -fmacro-prefix-map to make __FILE__ a relative path
Linux commit a73619a845d5625079cc1b3b820f44c899618388
The __FILE__ macro is used everywhere in the kernel to locate the file
printing the log message, such as WARN_ON(), etc. If the kernel is
built out of tree, this can be a long absolute path, like this:
WARNING: CPU: 1 PID: 1 at /path/to/build/directory/arch/arm64/kernel/foo.c:...
This is because Kbuild runs in the objtree instead of the srctree,
then __FILE__ is expanded to a file path prefixed with $(srctree)/.
Commit 9da0763bdd82 ("kbuild: Use relative path when building in a
subdir of the source tree") improved this to some extent; $(srctree)
becomes ".." if the objtree is a child of the srctree.
For other cases of out-of-tree build, __FILE__ is still the absolute
path. It also means the kernel image depends on where it was built.
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 and
more reproducible builds.
Please note __FILE__ is always an absolute path for external modules.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r-- | Makefile | 3 |
1 files changed, 3 insertions, 0 deletions
@@ -486,6 +486,9 @@ CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) # disable pointer signed / unsigned warnings in gcc 4.0 CFLAGS += $(call cc-option,-Wno-pointer-sign,) +# change __FILE__ to the relative path from the srctree +CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=) + # KBUILD_IMAGE: Default barebox image to build # Depending on the architecture, this can be either compressed or not. # It will also include any necessary headers to be bootable. |