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

[Cornelia Huck <cohuck@redhat.com>]

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?