On Wed, 23 Nov 2016, Mike Belopuhov wrote:
> > I guess we could do that. But then we cannot free the mbufs on DOWN
> > until the device has used them.
>
> Diff to this effect is below. Works on vmd and qemu (original
> one didn't because I kept the virtio_reset).
>
> > That sounds like an unnecessary waste of memory to me.
> >
>
> This is not so much memory we lose and then if you up it again
> you're going to have it all back. We can revert to the present
> behavior once vmd matures, in the meantime people won't have to
> juggle diffs around in their trees :)
I am not convinced. Doing a reset allows to recover from all kinds of
problems with DOWN/UP. That was useful when we had bugs in the event_idx
implementation.
Also, I don't like to change code that is known to work with at least 4
independent device implementations to work around problems in one
incomplete implementation that we can easily change.
Maybe something like this is enough already (untested):
--- usr.sbin/vmd/virtio.c 2016-10-20 05:05:49.049943724 +0200
+++ usr.sbin/vmd/virtio.c 2016-11-23 08:55:38.829501275 +0100
@@ -796,6 +796,9 @@
ret = 0;
+ if (dev->cfg.device_status != VIRTIO_CONFIG_DEVICE_STATUS_DRIVER_OK)
+ return ret;
+
vr_sz = vring_size(VIONET_QUEUE_SIZE);
q_gpa = dev->vq[0].qa;
q_gpa = q_gpa * VIRTIO_PAGE_SIZE;
