Re: [PATCH RFC 1/2] Makefile: Never use -fno-omit-frame-pointer
On Sat, Jul 18, 2009 at 02:01:45PM +0200, Ingo Molnar wrote: * Anton Vorontsov avoront...@ru.mvista.com wrote: On Wed, Jun 17, 2009 at 12:16:30AM +0400, Anton Vorontsov wrote: According to Segher Boessenkool and GCC manual, -fomit-frame-pointer is only the default when optimising on archs/ABIs where it doesn't hinder debugging and -pg. So, we do not get it by default on x86, not at any optimisation level. On the other hand, *using* -fno-omit-frame-pointer causes gcc to produce buggy code on PowerPC targets. If Segher and GCC manual are right, this patch should be a no-op for all arches except PowerPC, where the patch fixes gcc issues. Signed-off-by: Anton Vorontsov avoront...@ru.mvista.com --- See this thread for more discussion: http://osdir.com/ml/linux-kernel/2009-05/msg01754.html p.s. Obviously, I didn't test this patch on anything else but PPC32. ;-) Segher, do you know if all GCC versions that we support for building Linux are behaving the way that GCC manual describe? No news is good news... Ingo, can we merge this into -tip for testing? Changes to the top level Makefile should really go via Sam's kbuild tree. Sam, any thoughts about these patches? Thanks! -- Anton Vorontsov email: cbouatmai...@gmail.com irc://irc.freenode.net/bd2 ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH RFC 1/2] Makefile: Never use -fno-omit-frame-pointer
[Sorry for not replying earlier, somehow I missed this mail] On the other hand, *using* -fno-omit-frame-pointer causes gcc to produce buggy code on PowerPC targets. It doesn't cause the problem, it only exposes it. And, of course, only on certain GCC versions. Segher, do you know if all GCC versions that we support for building Linux are behaving the way that GCC manual describe? I believe so, yes. Segher ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
[PATCH RFC 1/2] Makefile: Never use -fno-omit-frame-pointer
According to Segher Boessenkool and GCC manual, -fomit-frame-pointer is only the default when optimising on archs/ABIs where it doesn't hinder debugging and -pg. So, we do not get it by default on x86, not at any optimisation level. On the other hand, *using* -fno-omit-frame-pointer causes gcc to produce buggy code on PowerPC targets. If Segher and GCC manual are right, this patch should be a no-op for all arches except PowerPC, where the patch fixes gcc issues. Signed-off-by: Anton Vorontsov avoront...@ru.mvista.com --- See this thread for more discussion: http://osdir.com/ml/linux-kernel/2009-05/msg01754.html p.s. Obviously, I didn't test this patch on anything else but PPC32. ;-) Segher, do you know if all GCC versions that we support for building Linux are behaving the way that GCC manual describe? Thanks, Makefile |2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/Makefile b/Makefile index ea63667..70ad1ff 100644 --- a/Makefile +++ b/Makefile @@ -535,7 +535,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) endif ifdef CONFIG_FRAME_POINTER -KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls +KBUILD_CFLAGS += -fno-optimize-sibling-calls else KBUILD_CFLAGS += -fomit-frame-pointer endif -- 1.6.3.1 ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
