On 17 January 2014 01:16, Chris Friesen <[email protected]> wrote:
> On 01/16/2014 05:12 PM, CARVER, PAUL wrote: > > Jumping back to an earlier part of the discussion, it occurs to me >> that this has broader implications. There's some discussion going on >> under the heading of Neutron with regard to PCI passthrough. I >> imagine it's under Neutron because of a desire to provide passthrough >> access to NICs, but given some of the activity around GPU based >> computing it seems like sooner or later someone is going to try to >> offer multi-tenant cloud servers with the ability to do GPU based >> computing if they haven't already. >> > > I'd expect that the situation with PCI passthrough may be a bit different, > at least in the common case. > > The usual scenario is to use SR-IOV to have a single physical device > expose a bunch of virtual functions, and then a virtual function is passed > through into a guest. > That entirely depends on the card in question. Some cards support SRIOV and some don't (you wouldn't normally use SRIOV on a GPU, as I understand it, though you might reasonably expect it on a modern network card). Even on cards that do support SRIOV there's nothing stopping you assigning the whole card. But from the discussion here it seems that (whole card passthrough) + (reprorgrammable firmware) would be the danger, and programmatically there's no way to tell from the passthrough code in Nova whether any given card has programmable firmware. It's a fairly safe bet you can't reprogram firmware permanently from a VF, agreed. -- Ian.
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