From 426e3e0af5d2473e67d4256fc1340b7faebd1cc7 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 4 Feb 2008 23:49:59 -0500 Subject: virtio: clarify NO_NOTIFY flag usage The other side (host) can set the NO_NOTIFY flag as an optimization, to say "no need to kick me when you add things". Make it clear that this is advisory only; especially that we should always notify when the ring is full. Signed-off-by: Rusty Russell --- include/linux/virtio_ring.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include/linux/virtio_ring.h') diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index ea3be89..abe481e 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -15,9 +15,13 @@ /* This marks a buffer as write-only (otherwise read-only). */ #define VRING_DESC_F_WRITE 2 -/* This means don't notify other side when buffer added. */ +/* The Host uses this in used->flags to advise the Guest: don't kick me when + * you add a buffer. It's unreliable, so it's simply an optimization. Guest + * will still kick if it's out of buffers. */ #define VRING_USED_F_NO_NOTIFY 1 -/* This means don't interrupt guest when buffer consumed. */ +/* The Guest uses this in avail->flags to advise the Host: don't interrupt me + * when you consume a buffer. It's unreliable, so it's simply an + * optimization. */ #define VRING_AVAIL_F_NO_INTERRUPT 1 /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ -- cgit v1.1