Re: [PATCH 06/18] virtio_ring: avail event index interface
From: Rusty Russell <hidden>
Date: 2011-05-09 05:53:57
Also in:
kvm, linux-s390, lkml
On Wed, 4 May 2011 23:51:19 +0300, "Michael S. Tsirkin" [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Define a new feature bit for the host to declare that it uses an avail_event index (like Xen) instead of a feature bit to enable/disable interrupts. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- include/linux/virtio_ring.h | 11 ++++++++--- 1 files changed, 8 insertions(+), 3 deletions(-)diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index f5c1b75..f791772 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h@@ -32,6 +32,9 @@ /* The Guest publishes the used index for which it expects an interrupt * at the end of the avail ring. Host should ignore the avail->flags field. */ #define VIRTIO_RING_F_USED_EVENT_IDX 29 +/* The Host publishes the avail index for which it expects a kick + * at the end of the used ring. Guest should ignore the used->flags field. */ +#define VIRTIO_RING_F_AVAIL_EVENT_IDX 32
Are you really sure we want to separate the two? Seems a little simpler to have one bit to mean "we're publishing our threshold". For someone implementing this from scratch, it's a little simpler. Or are there cases where the old style makes more sense? Thanks, Rusty.