[Xen-devel] RE: [PATCH][VTD][QUIRK] added quirks for Sandybridge errata workaround, WLAN, VT-d fault escalation

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 20.01.11 at 00:40, "Kay, Allen M" <allen.m.kay@xxxxxxxxx> wrote:
>>  To me it would seem more logical to add a usage counter: When
>> transitioning from zero, suppress RC6, and when transitioning to
>> zero, re-enable RC6 (whatever this is). If what gets written in
>> the preamble is some sort of counter the hardware decrements,
>> you would need to extend the period each time execution flows
>> through the preamble.
> 
> I see what you are getting at ...  Another alternative is to simply putting 
> the lock around the "preamble->iotlb_flush->postamble" sequence in iommu.c.  
> It 
> spills more of the quirk specific code into iommu.c but this should be much 
> simpler logic wise.  What do you think?

Wouldn't that result in excessive lock holding time?

Jan


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