Re: [Qemu-devel] [PATCH 1/2] [RFC] Make vmport report the processor speed

[Alexander Graf]

On 07.01.2009, at 12:32, François Revol wrote:

> > > > I don't think doing vmware esx in qemu in vmware us that much of a
> > > > valid scenario right now ;).
> > > >
> > > > But I agree with anthony here - not telling vmware esx that it's
> > > > running virtualized might be the best.
> > >
> > > As I said, it would not only benefit esx.
> > > Haiku also would likely work much better this way, and possibly
> > > BeOS
> > > with a small driver to recalibrate it (I already rewrote such a
> > > driver
> > > once, but it was just forcing it using a value from some settings
> > > that
> > > were to be taken from a real machine).
> >
> > If you really need to get the TSC speed, it might be best to use
> > official MSRs for that. The Intel documentation definitely includes
> > such an MSR.
>
> Oh, right then, more portable... though I wonder how they work with
> speedstep...

AFAIK the TSC value register is only available if constant_tsc is  
given. This is pretty much true for all VMX/SVM capable machines I'm  
aware of.

> Do we implement them yet ? grep got me some MSR_IA32_TSC in kvm.c,  
> so I
> suppose yes.

That is the TSC value MSR I guess. So no, we don't implement them yet.  
But that sounds like a way better interface to me than the VMware  
backdoor ;).

> Oh, I didn't notice rdtscp, might be interesting to use instead for
> Haiku.

Maybe using a PV clocksource is even better ...

Alex