Re: [RFC PATCH v2 1/2] Add virtio Admin Virtqueue specification

[Cornelia Huck <cohuck@redhat.com>]

On Wed, Jul 28 2021, "Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Tue, Jul 27, 2021 at 06:29:49PM +0300, Max Gurtovoy wrote:
>> Vendor specific is also important to allow vendors develop their special
>> souse.
>
> Most of the value of virtio is that it's generic.
> So we added VIRTIO_PCI_CAP_VENDOR_CFG which is very easy for
> the hypervisor to intercept. Maybe that is not enough but that
> needs justification, I am not sure it's a good idea to add multiple
> ways devices can differ without a lot of thought.

Agreed, we should be careful about adding devices that differ in a lot
of little things.

My thought is that the default should be to concentrate on common
features that can be specified, just to keep things movable between
different implementations. If a device is really very different from the
generic one, it should probably become a different device type. But my
preference would be that everyone tries to make their device stick to
a common specification.