Messages in this thread | | | Subject | Re: [RFC] /dev/ioasid uAPI proposal | From | Lu Baolu <> | Date | Tue, 1 Jun 2021 13:23:07 +0800 |
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Hi Jason W,
On 6/1/21 1:08 PM, Jason Wang wrote: >>> 2) If yes, what's the reason for not simply use the fd opened from >>> /dev/ioas. (This is the question that is not answered) and what happens >>> if we call GET_INFO for the ioasid_fd? >>> 3) If not, how GET_INFO work? >> oh, missed this question in prior reply. Personally, no special reason >> yet. But using ID may give us opportunity to customize the management >> of the handle. For one, better lookup efficiency by using xarray to >> store the allocated IDs. For two, could categorize the allocated IDs >> (parent or nested). GET_INFO just works with an input FD and an ID. > > > I'm not sure I get this, for nesting cases you can still make the child > an fd. > > And a question still, under what case we need to create multiple ioasids > on a single ioasid fd?
One possible situation where multiple IOASIDs per FD could be used is that devices with different underlying IOMMU capabilities are sharing a single FD. In this case, only devices with consistent underlying IOMMU capabilities could be put in an IOASID and multiple IOASIDs per FD could be applied.
Though, I still not sure about "multiple IOASID per-FD" vs "multiple IOASID FDs" for such case.
Best regards, baolu
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