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SubjectRe: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue

* Thomas Gleixner <tglx@linutronix.de> wrote:

> On Wed, 25 Nov 2009, Ingo Molnar wrote:
> > * Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > > On Tue, 24 Nov 2009, Jakub Jelinek wrote:
> > >
> > > > On Tue, Nov 24, 2009 at 03:55:49PM +0100, Thomas Gleixner wrote:
> > > > > > you should compile your code with -maccumulate-outgoing-args, and there's
> > > > > > no need to use -mtune=generic. Is that right?
> > > > >
> > > > > Seems to work. What other side effects has that ?
> > > >
> > > > Faster code, significant increase in code size though. Note that on many
> > > > architectures it is the only supported model.
> > >
> > > Just checked on the affected -marchs. The increase in code size is
> > > about 3% which is not that bad and definitely acceptable for the
> > > tracing case. Will zap the -mtune=generic patch and use
> > > -maccumulate-outgoing-args instead.
> >
> > hm, 3% sounds quite large :( dyn-ftrace is enabled in distro configs, so
> > 3% is a big deal IMO.
>
> Distro-configs have -mtune=generic anyway. So it's not changing
> anything for them.
>
> I'm talking about the -march flags which result in that weird code
> (pentium-mmx ....).

ok!

Ingo


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