On Tue, 12 Apr 2011 23:01:12 +0300, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > On Thu, Mar 10, 2011 at 12:19:42PM +1030, Rusty Russell wrote: > > Here's an old patch where I played with implementing this: > > ... > > > > > virtio: put last_used and last_avail index into ring itself. > > > > Generally, the other end of the virtio ring doesn't need to see where > > you're up to in consuming the ring. However, to completely understand > > what's going on from the outside, this information must be exposed. > > For example, if you want to save and restore a virtio_ring, but you're > > not the consumer because the kernel is using it directly. > > > > Fortunately, we have room to expand: > > This seems to be true for x86 kvm and lguest but is it true > for s390? Yes, as the ring is page aligned so there's always room. > Will this last bit work on s390? > If I understand correctly the memory is allocated by host there? They have to offer the feature, so if the have some way of allocating non-page-aligned amounts of memory, they'll have to add those extra 2 bytes. So I think it's OK... Rusty. -- 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
