RE: [Xen-devel] [PATCH]ACPI: re-enable mwait for xen cpuidle

["Wei, Gang" <gang.wei@xxxxxxxxx>]

On Friday, 2010-4-2 1:41 PM, Jeremy Fitzhardinge wrote:
> On 04/01/2010 07:38 PM, Wei, Gang wrote:
>> I suggest including this patch in Xen 4.0 release. It is quite
>> straightforward, and make sure the better and widely equipped cpu
>> idle entry method MWAIT is used by xen if available.  
>> 
>> BTW, can we consider re-open MWAIT freature for dom0 in xen
>> hypervisor? We can discuss it post 4.0. 
>> 
>> Jimmy
>> 
>> ACPI: re-enable mwait for xen cpuidle
>> 
>> Xen hypervisor doesn't export mwait feature to dom0, but latest
>> Linux kernel start to check this feature while initializing _PDC
>> object. Bypass such check in pv-ops case to re-enable mwait for xen
>> cpuidle.   
>> 
> 
> Why not just set or clear the MWAIT feature flag in xen_cpuid?

Yes, you pointed out another approach in dom0 side which has similar effect as 
re-open MWAIT feature for dom0 in xen. I am not sure whether exposing the MWAIT 
feature to whole dom0 kernel is ok. My way is just to narrow the impact.

Jimmy


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