Re: [Xen-devel] Xen cpufreq support status: how to notify hypervisor of frequency change?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 11 Apr 2006, at 01:05, Matt T. Yourst wrote:

> Note that I only implemented this for powernow-k8 right now, since 
> that's the
> only hardware I could test it on. It's very obvious how to adapt it to 
> the
> other cpufreq drivers, by just replacing rdmsr and wrmsr with the Xen 
> wrapper
> versions I provided, and adding in the setcpufreq hypercall at the end.
All this stuff should be done by emulating the MSR writes in 
emulate_privileged_op() in arch/x86/traps.c. This will avoid any 
modification of Linux at all. Currently there's only simple filtering 
of MSR write attempts, but picking up on cpu-freq MSR accesses on e.g., 
AMD systems and also resync'ing the local clock would not be difficult.
 -- Keir


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