* Arnaldo Carvalho de Melo <a...@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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