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

[Cornelia Huck <cohuck@redhat.com>]

On Mon, Aug 02 2021, "Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Mon, Aug 02, 2021 at 07:03:11PM +0300, Max Gurtovoy wrote:
>> There is no much bits left in the generic feature field for all the features
>> we would like to add.
>> I mentioned only 5-6 in the above example and it will bring us to bit 46
>> already.
>> 
>> please think of 5-10 years from today.
>> 
>
> IIUC nothing prevents adding more once we exhaust 64 bits. IMHO it's actually
> pretty important to make sure the feature negotiation works well
> and covers relevant usecases. If we have limitations preventing that
> I'd like to at least try to fix that not replacing feature negotiation with
> something else.

I recall that we had a discussion about that years ago when we
introduced VERSION_1; we explicitly agreed that we can extend features
beyond 64 bit once we need it. (A quick search did not turn up that mail
exchange, though.)