Re: [git pull] x86 PAT changes

Ingo Molnar
2008-04-26T15:41:52Z

* Gabriel C <nix.or.die@googlemail.com> wrote:

> Ingo Molnar wrote:
> > * Gabriel C <nix.or.die@googlemail.com> wrote:
> >
> >> Hi Ingo,
> >>
> >> When using an 64bit ( didn't got time to test 32bit now ) kernel[1]
> >> with PAT enabled , kvm-intel does not work anymore.
> >>
> >> When modprobing kvm-intel , kvm is saying VT extension is disable by
> >> BIOS which isn't true. When disabling PAT again ( no changes to BIOS )
> >> kvm-intel works again here.
> >>
> >> Is that an known problem ?
> >
> > no, that side-effect was not known. Cc:-ed more folks.
>
> It seems like the update triggers some compiler bug.
>
> Setting CC_OPTIMIZE_FOR_SIZE=n fixed that btw.
>
> I don't have the time right now but later on today I will compile
> gcc43_svn_branch and test again with CC_OPTIMIZE_FOR_SIZE=y and see
> what I get.
>
> Ingo sorry for the noise.

no problem and it's not noise even if it turns out to be a compiler
problem - we very much want to know about them when they affect the
kernel.

Ingo