Re: [virtio-comment] RE: [PATCH v3 2/2] content: Support enabling virtqueue after DRIVER_OK stage

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 18, 2023 at 01:03:57PM +0200, Cornelia Huck wrote:
> On Wed, Oct 18 2023, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Wed, Oct 18, 2023 at 12:25:23PM +0200, Cornelia Huck wrote:
> >> On Tue, Oct 17 2023, Parav Pandit <parav@nvidia.com> wrote:
> >> 
> >> >> From: Cornelia Huck <cohuck@redhat.com>
> >> >> Sent: Tuesday, October 17, 2023 5:55 PM
> >> >> 
> >> >> On Mon, Oct 02 2023, Parav Pandit <parav@nvidia.com> wrote:
> >> >> > +When VIRTIO_F_RING_DYNAMIC is not negotiated, the driver MUST enable
> >> >> > +the required number of virtqueues before setting the DRIVER_OK status bit.
> >> >> 
> >> >> What does "required" mean here? It just chooses to enable the queues it wants
> >> >> to use, right?
> >> > Right.
> >> > Required meaning, whatever number of queues that driver choose to enable, those must be enabled before driver_ok.
> >> > So it is "required by the driver".
> >> > Would that be ok?
> >> 
> >> I'd write it as "the driver MUST enable any virtqueue it plans to use"
> >> or something like that.
> >> 
> >> (...)
> >
> > It would have to be SHOULD - we can't add new MUST requirements not
> > contingent on a feature bit, we can give recommendation based on
> > existing installed base.
> 
> Then I wonder whether we need to add any normative statement at all --
> prior to the introduction of this new feature, the driver had to enable
> anything it wanted to use before DRIVER_OK, and if it does not negotiate
> the new feature, nothing changes. Spelling that out in non-normative
> sections should be enough?

I think it's not a bad thing to be clearer, but I don't care much.

-- 
MST