translate the pfn to an mfn is sufficient
Actually, after thinking about this, it's a bit
more complicated because of the possibility that a DMA may
address more than one page. If so, a simple DMA may need to be
translated into a scatter-gather (or a scatter-gather into
a more complex scatter-gather).
Not impossible, obviously because Xen/x86 handles this -- by
changing Linux, correct?
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"?
Dan
-----Original Message-----
From: Ian Pratt [mailto:m+Ian....@cl.cam.ac.uk]
Sent: Tuesday, January 24, 2006 4:43 PM
To: Muli Ben-Yehuda; Magenheimer, Dan (HP Labs Fort Collins)
Cc: xen-devel; okr...@us.ibm.com; ian....@cl.cam.ac.uk
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.
4 messages in com.xensource.lists.xen-ia64-develRE: [Xen-devel] VP problematic for ba...