Messages in this thread | | | Date | Wed, 20 May 2015 16:55:06 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] perf: fix wrong DEBUG configuration |
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* Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> Em Wed, May 20, 2015 at 03:29:37PM +0200, Martin Liška escreveu: > > On 05/20/2015 03:17 PM, Arnaldo Carvalho de Melo wrote: > > >Em Wed, May 20, 2015 at 03:07:39PM +0200, Martin Liška escreveu: > > >>Currently, GCC optimizes -O6 same as -O3 level. Right optimize debugging > > >>experience is given by passing -Og to compiler. > > > >Is this is this -Og available in old gcc versions? When was it > > >introduced? Do you know? > > > GCC 4.8.0 is the first version capable of the option: https://gcc.gnu.org/gcc-4.8/changes.html. > > That can be problematic, which GCC version do you support in linux/perf? > > So the rule has been: What are the kernel requirements for the > toolchain? tools/perf/ should build with that.
So we could use -Og if it works, like Kbuild does it:
KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
the 'cc-option' Make function does some magic of silently calling GCC with that option and observing the result.
See:
scripts/Kbuild.include:cc-option = $(call try-run,\
et al.
Thanks,
Ingo
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