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Re: [Xen-devel] cpufreq support status

To: Jan Beulich <jbeulich@xxxxxxxxxx>, Mark Langsdorf <mark.langsdorf@xxxxxxx>
Subject: Re: [Xen-devel] cpufreq support status
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Wed, 17 Oct 2007 15:34:35 +0100
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On 17/10/07 15:20, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> The question is whether *any* of the cpufreq drivers will now work (with
> Xen properly adjusting to the changed frequency) versus whether this
> now can only be expected to work for powernow-k8 (plus perhaps
> acpi-cpufreq). In the latter case I'd likely continue to have the
> CPU_FREQ selector depend on !XEN in our kernels, instead of the
> more fragile disabling of individual drivers...
> 
> The cpufreq notifier would suggest it's generic, but the MSR accesses
> needed by other drivers would suggest it's not.

It's definitely k8-powernow only right now. acpi-cpufreq might work if the
control register is an i/o port. It won't work if the control register is an
MSR, since the MSR would not be whitelisted in the WRMSR emulation in
emulate_privileged_op().

 -- Keir



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