On Thu, Aug 06, 2020 at 11:23:05AM +0800, Jason Wang wrote: > > On 2020/8/5 下午7:40, Michael S. Tsirkin wrote: > > On Wed, Aug 05, 2020 at 02:14:07PM +0800, Jason Wang wrote: > > > On 2020/8/4 上午5:00, Michael S. Tsirkin wrote: > > > > Some legacy guests just assume features are 0 after reset. > > > > We detect that config space is accessed before features are > > > > set and set features to 0 automatically. > > > > Note: some legacy guests might not even access config space, if this is > > > > reported in the field we might need to catch a kick to handle these. > > > I wonder whether it's easier to just support modern device? > > > > > > Thanks > > Well hardware vendors are I think interested in supporting legacy > > guests. Limiting vdpa to modern only would make it uncompetitive. > > > My understanding is that, IOMMU_PLATFORM is mandatory for hardware vDPA to > work.
Hmm I don't really see why. Assume host maps guest memory properly, VM does not have an IOMMU, legacy guest can just work. Care explaining what's wrong with this picture? > So it can only work for modern device ... > > Thanks > > > > > > > >
