On Thu, May 05, 2011 at 09:34:46AM +0100, Stefan Hajnoczi wrote: > On Wed, May 4, 2011 at 9:51 PM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > With the new used_event and avail_event and features, both > > host and guest need similar logic to check whether events are > > enabled, so it helps to put the common code in the header. > > > > Note that Xen has similar logic for notification hold-off > > in include/xen/interface/io/ring.h with req_event and req_prod > > corresponding to event_idx + 1 and new_idx respectively. > > +1 comes from the fact that req_event and req_prod in Xen start at 1, > > while event index in virtio starts at 0. > > > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > --- > > include/linux/virtio_ring.h | 14 ++++++++++++++ > > 1 files changed, 14 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h > > index f791772..2a3b0ea 100644 > > --- a/include/linux/virtio_ring.h > > +++ b/include/linux/virtio_ring.h > > @@ -124,6 +124,20 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) > > + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num; > > } > > > > +/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ > > +/* Assuming a given event_idx value from the other size, if > > s/other size/other side/ ? > > Stefan Exactly. Good catch, thanks. -- MST -- 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
