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RE: [Xen-ia64-devel] RE: [Xen-devel] VP problematic for backend driverson IA64?

>From: Magenheimer,Dan (HP Labs Fort Collins)
>Sent: 2006年1月25日 8:03
>Do hardware IOMMU's in general handle this complication?
>E.g. is there a cleanly defined interface that can be applied
>to a VP domain "Xen IOMMU"?

If drivers conform to DMA interface, that's the cleanly defined one.

>> -----Original Message-----
>> From: Ian Pratt [mailto:m+Ian.Pratt@xxxxxxxxxxxx]
>> Sent: Tuesday, January 24, 2006 4:43 PM
>> To: Muli Ben-Yehuda; Magenheimer, Dan (HP Labs Fort Collins)
>> Cc: xen-devel; okrieg@xxxxxxxxxx; ian.pratt@xxxxxxxxxxxx
>> Subject: RE: [Xen-devel] VP problematic for backend drivers on IA64?
>> > I understand that during the IA64 session at the summit there
>> > was some discussion on VP being problematic for the current
>> > backend drivers (or the other way around), and IOMMUs were
>> > suggested as a possible solution. Could you please elaborate
>> > on what's the problem?
>> It's simply that the actual DMA operations need to use machine
>> addresses. Ideally, you'd use an iommu to translate/partition, but in
>> the absence of an iommu simply enabling a privileged domain
>> to read its
>> p2m table and translate the pfn to an mfn is sufficient.
>> Ian
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