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Re: [Xen-devel] [PATCH][Retry 1] 4/4: cpufreq/PowerNow! in Xen: PowerNow

To: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH][Retry 1] 4/4: cpufreq/PowerNow! in Xen: PowerNow! changes
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 31 Aug 2007 18:44:55 +0100
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On 31/8/07 17:56, "Langsdorf, Mark" <mark.langsdorf@xxxxxxx> wrote:

>> Should we have a copy of that file in powernow-k8-xen.c? Can
>> the patched file work correctly in a native Linux build?
> The patch is the same patch I submitted upstream for the native
> 2.6.23 Linux kernel.
> In native mode, the kernel creates a cpumask for each cpu that
> lists its sibling cores.  Unfortunately, Xen doesn't do that.
> The patch instead reads and parses the _PSD ACPI structure,
> which indicates which cores share pstates with other cores.
> (Frankly, _PSD is the right way to do it, but the other way
> was easier until Linux got ACPI support for _PSD).  If Xen
> were using the same kernel version as Linux, the patch wouldn't
> be necessary.

Okay, that was the other possibility. :-) Fine then!

 -- Keir

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