Re: [PATCH 1/1] Speedfreq-SMI call clobbers ECX

Stephan Diestelhorst
2008-03-10T23:15:28Z

Stephan Diestelhorst wrote:
> Andi Kleen wrote:
> > Stephan Diestelhorst <langer_mann@web.de> writes:
> > >
> > > New attempt with full clobbers, note that I deliberatly did not change
> > > the order of the output registers. Real output operands still preceede
> > > outputs used for potential clobbering.
> > >
> > > I'm not too sure about the EBP push/pop frame, but as folks pointed
> > > out already, we should not trust the SMI code too much.
> >
> > Be careful -- older gcc versions tend to abort for inline asm
> > that clobbers too many registers. Especially when the register
> > is already used (like ebp in a frame pointer enabled kernel)
>
> > Make sure it at least works on the oldest supported gcc version
> > (gcc 3.2) and with frame pointer on.
>
> As I've said, I do not expect this to be problematic, but will test,
> just to be sure!

I've tried it on the following GCCs: 3.3, 3.4, 4.0, 4.1, all with and
without frame-pointer ommission.
Result: As expected. Worked w/o problems, warnings anything.

Apologies for not testing gcc-3.2, but compiling it from source did
not work with libtool complaining about tags in libmath. I'd be
grateful if someone with working gcc-3.2 could try this out.

Cheers,
Stephan