| Message ID | 20190831180113.16025-2-itsatharva@gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2,1/2] toolchain/toolchain-wrapper: explicitly set Build ID to none if BR2_REPRODUCIBLE | expand |
Hi Atharva, Le 31/08/2019 à 20:01, Atharva Lele a écrit : > Many tools use __FILE__ for debugging and __FILE__ captures the build path. > This results in non-reproducible images when building in different directories. Based on the commit log in gcc adding this option [1], -ffile-prefix-map also remap file names in __BASE_FILE__ and __builtin_FILE(). Specifying -ffile-prefix-map option is equivalent to specifying all the individual options -f*-prefix-map (-fmacro-prefix-map and -fdebug-prefix-map). [1] https://github.com/gcc-mirror/gcc/commit/859b51f83662d01e4f158ea9327db9ca37fe70b3 > > If the config uses GCC 8 or above, we use -ffile-prefix-map=old=new and let gcc > take care of the path remapping in __FILE__. Since GCC versions before v8 did > not have this feature, we use a dummy string in that case. > > Signed-off-by: Atharva Lele <itsatharva@gmail.com> > --- > Changes v2: > - New patch > --- > toolchain/toolchain-wrapper.mk | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk > index 88695a5b2d..6d0ae2c85b 100644 > --- a/toolchain/toolchain-wrapper.mk > +++ b/toolchain/toolchain-wrapper.mk > @@ -23,6 +23,11 @@ TOOLCHAIN_WRAPPER_OPTS = \ > > ifeq ($(BR2_REPRODUCIBLE),y) > TOOLCHAIN_WRAPPER_OPTS += -Wl,--build-id=none > +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_8),y) > +TOOLCHAIN_WRAPPER_OPTS += -ffile-prefix-map=$(BASE_DIR)=buildroot > +else > +TOOLCHAIN_WRAPPER_OPTS += -D__FILE__=\"file-path-replaced-by-buildroot-for-reproducibility\" Maybe __BASE_FILE__ should be handle here too in order to have the save behaviour as -ffile-prefix-map. I'm not sure about __builtin_FILE(). Best regards, Romain > +endif > endif > > # We create a list like '"-mfoo", "-mbar", "-mbarfoo"' so that each flag is a >
On Sat, Sep 7, 2019 at 8:04 PM Romain Naour <romain.naour@smile.fr> wrote: > > Hi Atharva, > > Le 31/08/2019 à 20:01, Atharva Lele a écrit : > > Many tools use __FILE__ for debugging and __FILE__ captures the build path. > > This results in non-reproducible images when building in different directories. > > Based on the commit log in gcc adding this option [1], -ffile-prefix-map also > remap file names in __BASE_FILE__ and __builtin_FILE(). > > Specifying -ffile-prefix-map option is equivalent to specifying all the > individual options -f*-prefix-map (-fmacro-prefix-map and -fdebug-prefix-map). > > [1] > https://github.com/gcc-mirror/gcc/commit/859b51f83662d01e4f158ea9327db9ca37fe70b3 > > > > > If the config uses GCC 8 or above, we use -ffile-prefix-map=old=new and let gcc > > take care of the path remapping in __FILE__. Since GCC versions before v8 did > > not have this feature, we use a dummy string in that case. > > > > Signed-off-by: Atharva Lele <itsatharva@gmail.com> > > --- > > Changes v2: > > - New patch > > --- > > toolchain/toolchain-wrapper.mk | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk > > index 88695a5b2d..6d0ae2c85b 100644 > > --- a/toolchain/toolchain-wrapper.mk > > +++ b/toolchain/toolchain-wrapper.mk > > @@ -23,6 +23,11 @@ TOOLCHAIN_WRAPPER_OPTS = \ > > > > ifeq ($(BR2_REPRODUCIBLE),y) > > TOOLCHAIN_WRAPPER_OPTS += -Wl,--build-id=none > > +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_8),y) > > +TOOLCHAIN_WRAPPER_OPTS += -ffile-prefix-map=$(BASE_DIR)=buildroot > > +else > > +TOOLCHAIN_WRAPPER_OPTS += -D__FILE__=\"file-path-replaced-by-buildroot-for-reproducibility\" > > Maybe __BASE_FILE__ should be handle here too in order to have the save > behaviour as -ffile-prefix-map. You're right. I will update the patch to handle __BASE__FILE__ as well. > I'm not sure about __builtin_FILE(). I'm not sure either.. maybe we should keep it as is for now. Arnout, any thoughts on this? > > Best regards, > Romain > > > +endif > > endif > > > > # We create a list like '"-mfoo", "-mbar", "-mbarfoo"' so that each flag is a > > >
On 16/09/2019 13:54, Atharva Lele wrote: [snip] >> I'm not sure about __builtin_FILE(). > > I'm not sure either.. maybe we should keep it as is for now. > Arnout, any thoughts on this? There's no way to handle __builtin_FILE() correctly, because it's defined as a function, not a macro. However, we already don't handle __FILE__ correctly (since it should contain the actual file name, and not just a constant), so I guess doing something like -D__builtin_FILE()=\"...\" should work. BTW, now I think a bit more about this... The __FILE__ macro (and related) are used in 99% of the cases for debugging and logging output. Putting 'file-path-replaced-by-buildroot-for-reproducibility' there is hardly helpful. Maybe it would be better to just put the empty string. Romain, what do you think? Regards, Arnout
Hello, On Sat, 31 Aug 2019 23:31:13 +0530 Atharva Lele <itsatharva@gmail.com> wrote: > Many tools use __FILE__ for debugging and __FILE__ captures the build path. > This results in non-reproducible images when building in different directories. > > If the config uses GCC 8 or above, we use -ffile-prefix-map=old=new and let gcc > take care of the path remapping in __FILE__. Since GCC versions before v8 did > not have this feature, we use a dummy string in that case. > > Signed-off-by: Atharva Lele <itsatharva@gmail.com> I have applied this patch, with the following changes: [Thomas: - as suggested by Arnout, use the empty string for the __FILE__ and __BASE_FILE__ value - as suggested by Romain, also handle __BASE_FILE__ in addition to __FILE__ - pass -Wno-builtin-macro-redefined to avoid build errors when -Werror is passed] Best regards, Thomas
diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk index 88695a5b2d..6d0ae2c85b 100644 --- a/toolchain/toolchain-wrapper.mk +++ b/toolchain/toolchain-wrapper.mk @@ -23,6 +23,11 @@ TOOLCHAIN_WRAPPER_OPTS = \ ifeq ($(BR2_REPRODUCIBLE),y) TOOLCHAIN_WRAPPER_OPTS += -Wl,--build-id=none +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_8),y) +TOOLCHAIN_WRAPPER_OPTS += -ffile-prefix-map=$(BASE_DIR)=buildroot +else +TOOLCHAIN_WRAPPER_OPTS += -D__FILE__=\"file-path-replaced-by-buildroot-for-reproducibility\" +endif endif # We create a list like '"-mfoo", "-mbar", "-mbarfoo"' so that each flag is a
Many tools use __FILE__ for debugging and __FILE__ captures the build path. This results in non-reproducible images when building in different directories. If the config uses GCC 8 or above, we use -ffile-prefix-map=old=new and let gcc take care of the path remapping in __FILE__. Since GCC versions before v8 did not have this feature, we use a dummy string in that case. Signed-off-by: Atharva Lele <itsatharva@gmail.com> --- Changes v2: - New patch --- toolchain/toolchain-wrapper.mk | 5 +++++ 1 file changed, 5 insertions(+)