Re: [kvm-devel] [Qemu-devel] expose host CPU features to guests: Take 3

[Paul Brook]

On Tuesday 25 September 2007, Avi Kivity wrote:
> J. Mayer wrote:
> > On Tue, 2007-09-25 at 11:01 +0200, Avi Kivity wrote:
> >> Dan Kenigsberg wrote:
> >>> On Tue, Sep 25, 2007 at 03:28:24AM +0200, andrzej zaborowski wrote:
> >>>> Hi,
> >>>>
> >>>> On 24/09/2007, Dan Kenigsberg <address@hidden> wrote:
> >>>>> As with previous "Takes" of this patch, its purpose is to expose host
> >>>>> +{
> >>>>> +    asm("cpuid"
> >>>>> +        : "=a" (*ax),
> >>>>> +          "=b" (*bx),
> >>>>> +          "=c" (*cx),
> >>>>> +          "=d" (*dx)
> >>>>> +        : "a" (function));
> >>>>> +}
> >>>>
> Indeed for regular qemu this is useless.  But it is useful for kqemu
> (for which there is support in mainline qemu), and for kvm (which we
> hope to merge one day).

And, as discussed before, it should be asking the hypervisor what features it 
supports instead of trying to guess from the cpuid output.

Paul