Re: guest / host buffer sharing ...

[Stefan Hajnoczi <stefanha@gmail.com>]

On Wed, Nov 6, 2019 at 10:51 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
> > > Reason is:  Meanwhile I'm wondering whenever "just use virtio-gpu
> > > resources" is really a good answer for all the different use cases
> > > we have collected over time.  Maybe it is better to have a dedicated
> > > buffer sharing virtio device?  Here is the rough idea:
> >
> > My concern is that buffer sharing isn't a "device".  It's a primitive
> > used in building other devices.  When someone asks for just buffer
> > sharing it's often because they do not intend to upstream a
> > specification for their device.
>
> Well, "vsock" isn't a classic device (aka nic/storage/gpu/...) either.
> It is more a service to allow communication between host and guest

There are existing applications and network protocols that can be
easily run over virtio-vsock, virtio-net, and virtio-serial to do
useful things.

If a new device has no use except for writing a custom code, then it's
a clue that we're missing the actual use case.

In the graphics buffer sharing use case, how does the other side
determine how to interpret this data?  Shouldn't there be a VIRTIO
device spec for the messaging so compatible implementations can be
written by others?

Stefan