On Thu, Mar 02, 2023 at 12:30:52PM +0100, Eugenio Perez Martin wrote: > > You need to pass this to guest. My point is that there is no reason to > > get it from the kernel driver. QEMU can figure out whether the flag is > > needed itself. > > > > Ok, I can see now how the HW device does not have all the knowledge to > offer this flag or not. But I'm not sure how qemu can know either. > > If qemu opens /dev/vhost-vdpa-N, how can it know it? It has no way to > tell if the device is sw or hw as far as I know. Am I missing > something? > > Thanks!
This is what I said earlier. You can safely assume vdpa needs this flag. Only exception is vduse and we don't care about performance there. -- MST
