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[Xen-devel] Re: expose MWAIT to dom0
- To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
- From: Keir Fraser <keir.xen@xxxxxxxxx>
- Date: Mon, 15 Aug 2011 09:10:31 +0100
- Cc: "Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>, "Wei, Gang" <gang.wei@xxxxxxxxx>
- Delivery-date: Mon, 15 Aug 2011 01:13:13 -0700
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- Thread-topic: expose MWAIT to dom0
On 15/08/2011 08:57, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>> Else the kernel could get the flag from the real non paravirtualised CPUID
>> instruction.
>
> linux uses cpu_has to extract mwait capability. To use real cpuid instruction,
> then
> we need change Linux code which is not worthy though, like below:
> if (!cpu_has(c, X86_FEATURE_MWAIT))
> buf[2] &= ~(ACPI_PDC_C_C2C3_FFH);
> If we make it into cpu_has bits, then it lacks of original guarding effect.
cpu_has() accesses a pre-filled capabilities bitmask, filled from cpuid,
right? And cpuid goes through a pv_ops hook?
-- Keir
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