Re: [git pull] x86 fixes (NOPL issue)

[Robert Hancock]

Yinghai Lu wrote:
> On Fri, Sep 5, 2008 at 7:22 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> > Hi Linus,
> >
> > Please pull:
> >
> >  git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-fixes-for-linus-2
> >
> > H. Peter Anvin (4):
> >      x86: boot: stub out unimplemented CPU feature words
>  diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> > index 80ab20d..0785b3c 100644
> > --- a/arch/x86/kernel/cpu/common.c
> > +++ b/arch/x86/kernel/cpu/common.c
> > @@ -13,6 +13,7 @@
> >  #include <asm/mtrr.h>
> >  #include <asm/mce.h>
> >  #include <asm/pat.h>
> > +#include <asm/asm.h>
> >  #ifdef CONFIG_X86_LOCAL_APIC
> >  #include <asm/mpspec.h>
> >  #include <asm/apic.h>
> > @@ -341,6 +342,35 @@ static void __init early_cpu_detect(void)
> >        early_get_cap(c);
> >  }
> >
> > +/*
> > + * The NOPL instruction is supposed to exist on all CPUs with
> > + * family >= 6, unfortunately, that's not true in practice because
> > + * of early VIA chips and (more importantly) broken virtualizers that
> > + * are not easy to detect.  Hence, probe for it based on first
> > + * principles.
> > + */
>
> if so, should only test on VIA chips.

The virtual CPUs are more of a problem. They can't be distinguished from 
the real CPU models they are emulating other than by actually testing.
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