Re: [virtio-dev] [PATCH] virtio-net: use mtu size as buffer length for big packets

[Jason Wang <jasowang@redhat.com>]

On Tue, Aug 9, 2022 at 5:25 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Tue, Aug 09, 2022 at 03:44:22PM +0800, Jason Wang wrote:
> > > +             unsigned int mtu = vi->dev->mtu;
>
> BTW should this not be max_mtu?

Yes.

> Otherwise if user configures mtu that
> is too small we'll add buffers that are too small.  some backends simply
> lock up if this happens (I think vhost does).

Probably not? If we run out of buffers, we will wait for the next
kick. (Otherwise it would be an guest triggerable behaviour)

> Maybe we should add a feature to allow packet drop if it's too small.

I may miss something but isn't this what most devices will do? (e.g
ethernet have a minimal packet length)

Thanks

> And send mtu guest to host while we are at it?
>
> --
> MST
>