On Thu, Feb 01, 2018 at 06:48:54PM +0200, Michael S. Tsirkin wrote: > On Thu, Feb 01, 2018 at 02:31:32PM -0200, Eduardo Habkost wrote: > > On Thu, Feb 01, 2018 at 04:24:30PM +0200, Michael S. Tsirkin wrote: > > [...] > > > The full fix would be to allow QEMU to map a list of > > > pages to a guest supplied IOVA. > > > > Thanks, that's what I expected. > > > > While this is not possible, the only requests I have for this > > patch is that we clearly document: > > * What's the only purpose of share=on on a host-memory-backend > > object (due to pvrdma limitations). > > * The potential undesirable side-effects of setting share=on. > > * On the commit message and other comments, clearly distinguish > > HVAs in the QEMU address-space from IOVAs, to avoid confusion. > > Looking forward, when we do support it, how will management find out > it no longer needs to pass the share parameter? > > Further, if the side effects of the share parameter go away, > how will it know these no longer hold?
A query-host-capabilities or similar QMP command seems necessary for that. It would be useful for other stuff like MAP_SYNC. -- Eduardo