Re: Intel/AMD Speedstep/PowerNow support

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

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.

Christoph