Re: [PATCH 3/3] virtio-net: graceful fallback to vhost=off for tap netdev

[Jason Wang]

On 2021/2/5 下午9:38, Michael S. Tsirkin wrote:
> On Thu, Feb 04, 2021 at 10:29:15PM +0200, Yuri Benditovich wrote:
> > Currently virtio-net silently clears features if they are
> > not supported by respective vhost. This may create migration
> > problems in future if vhost features on the source and destination
> > are different. Implement graceful fallback to no-vhost mode
> > when some acked features contradict with vhost. The decision is
> > taken on set_features call and the vhost will be disabled
> > till next reset (or migration).
> > Such fallback is currently enabled only for TAP netdev.
> >
> > Signed-off-by: Yuri Benditovich<yuri.benditovich@daynix.com>
> Sounds good, but I don't think we should do this if
> vhostforce=on is set.


If we do this, does it mean we won't maintain migration compatibility 
when vhostforce is on?

Thanks


> Also, let's document this behaviour with the vhost option so people
> are not suprized.