RE: [Xen-devel] AMD P-States not recognized for Xen 3.3 and 3.4

["Langsdorf, Mark" <mark.langsdorf@xxxxxxx>]

> > ... but was told that it is intentional that there's no 
> code to handle these.
> 
> Hm. And for what reason it does work in dom0-kernel? Because 
> it's done by powernow-k8.ko and userspace software?

Correct.  The family 0xf P-state interface is significantly
more complicated than the Family 0x10/architectural P-state
interface.  Porting it into the Xen hypervisor would possibly
introduce some more stability issues.  The architectural 
P-state interface is much stabler and smaller, and it made
sense to move it into Xen.  

Since the family 0xf P-state interface already existed in the
Linux kernel, it was easy enough to allow Linux dom0s to use
it for RevF systems.  Sadly, it's still got some problems 
due to the use of TSC as a time source.

-Mark Langsdorf
Operating System Research Center
AMD


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