On 18/08/2022 19.31, Vagrant Cascadian wrote: > From: Vagrant Cascadian <vagr...@reproducible-builds.org> > > The KBUILD_CFLAGS and KBUILD_AFLAGS variables are adjusted to use > -ffile-prefix-map and --debug-prefix-map, respectively, to use > relative paths for occurrences of __FILE__ and debug paths. > > This enables reproducible builds regardless of the absolute path to > the build directory: > > https://reproducible-builds.org/docs/build-path/ > > Signed-off-by: Vagrant Cascadian <vagr...@reproducible-builds.org> > > --- > > Makefile | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index 1a66f69a4b..b40b9b2444 100644 > --- a/Makefile > +++ b/Makefile > @@ -751,14 +751,18 @@ KBUILD_CFLAGS += $(call cc-disable-warning, > stringop-overflow) > # Enabled with W=2, disabled by default as noisy > KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) > > -# change __FILE__ to the relative path from the srctree > -KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=) > +# change __FILE__ and debugging symbols to the relative path from the > +# srctree > +KBUILD_CFLAGS += $(call cc-option,-ffile-prefix-map=$(srctree)/=)
You do update the comment, but it might be worth spelling out in the commit log that -ffile-prefix-map is a superset of -fmacro-prefix-map, and that both options are supported in the same set of compilers (so we don't lose the effect of -fmacro-prefix-map for some set of compilers), namely gcc 8. For reference, from the gcc repo commit 7365279fca30371b07e49bfa83a23ddc44cc3860 Author: Boris Kolpackov <bo...@gcc.gnu.org> Date: Thu Jan 18 13:17:37 2018 +0000 Add ability to remap file names in __FILE__, etc (PR other/70268) This commit adds the -fmacro-prefix-map option that allows remapping of file names in __FILE__, __BASE_FILE__, and __builtin_FILE(), similar to how -fdebug-prefix-map allows to do the same for debug information. Additionally, it adds -ffile-prefix-map which can be used to specify both mappings with a single option (and, should we need to add more -f*-prefix-map options in the future, those as well). > KBUILD_CFLAGS += -g > # $(KBUILD_AFLAGS) sets -g, which causes gcc to pass a suitable -g<format> > # option to the assembler. > KBUILD_AFLAGS += -g > > +# Use relative paths in debugging symbols > +KBUILD_AFLAGS += --debug-prefix-map=$(srctree)/= > + Hm, ok, it seems this has been supported in binutils since ~2007, so I don't suppose this needs some equivalent to the cc-option guard. Acked-by: Rasmus Villemoes <rasmus.villem...@prevas.dk>
