Messages in this thread | | | Subject | Re: [RFC] /dev/ioasid uAPI proposal | From | Jason Wang <> | Date | Tue, 1 Jun 2021 13:29:39 +0800 |
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在 2021/6/1 下午1:23, Lu Baolu 写道: > 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.
Right, that's exactly my question. The latter seems much more easier to be understood and implemented.
Thanks
> > Best regards, > baolu >
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