On Thu, 2012-07-26 at 19:06 +0300, Avi Kivity wrote: > On 07/26/2012 05:56 PM, Alex Williamson wrote: > > > > Both KVM and VFIO do strive to make the device in the guest look as much > > like it does on bare metal as possible, but we don't guarantee they're > > identical and we don't guarantee to match each other. > > btw, this is somewhat problematic, conceivably this could break a guest > (due to a guest bug). But with device assignment the compatibility > requirements can be relaxed a bit since there is no live migration. Well, I would hope that things work better in vfio and we work to make that the recommended method of device assignment. We can't hold one back to make things identical. The only barrier I see to this is that vfio focuses on security, enforcing things like ACS to make sure devices can't do DMA to other devices outside of the group whereas KVM assignment will let you attempt to do nearly anything and counts on libvirt to only let the user attempt to do sane things. As you say, there's no live migration with device assignment, so absolute identical config space is not a requirement and the difference we do have should be sufficiently subtle that the guest doesn't care boot-to-boot. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
