Re: Intel/AMD Speedstep/PowerNow support

[Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost>]

Christoph Egger wrote:
> Jean-Yves Migeon wrote:
> > Manuel Bouyer wrote:
> > > On Mon, Aug 03, 2009 at 10:50:42PM +0200, Jean-Yves Migeon wrote:
> > > > Good, now I know it works for amd64 too.
> > > time to commit, maybe ? :)
> > Yep, sorry for delay; done.
>
> Nice work, but I don't believe it is complete.
>
> With PowerNow, CPU changes its frequencies.
> You need to use the XENPF_change_freq platform_op hypercall
> to sync Dom0 and Xen that the frequence changed.
> Without this, we run into timing troubles,
> i.e. "time went backward", "Time too fast in domU X", etc.

> For PowerNow support newer than AMD K8 CPUs, you
> need the XENPF_set_processor_pminfo platform_op hypercall.

Okay, I'll have a look. Thanks for pointing that out.

--
Jean-Yves Migeon
jeanyves.migeon%free.fr@localhost