Re: [virtio-comment] RE: [PATCH 1/2] virtio: introduce selective queue enabling

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

On Thu, Jun 08, 2023 at 01:15:46PM +0000, Parav Pandit wrote:
> 
> 
> > From: Eugenio Perez Martin <eperezma@redhat.com>
> > Sent: Thursday, June 8, 2023 7:54 AM
> 
> > > Yes, I have read it few times and every time I concluded that:
> > > it does not say that it must be done before DRIVER_OK and cannot be done
> > after DRIVER_OK.
> > >
> > 
> > I also read it this way to be honest. From a POV, to allow it if a device does not
> > handle it could be considered a fix, rather than an addition.
> > 
> > I'm assuming we need to modify the standard just because it was not explicitly
> > allowed. To explicitly allow it before DRIVER_OK was not needed because it was
> > already widespread.
> > 
> It was explicit enough that queues can be enabled after DRIVER_OK.

Weird, there's spec text saying they can't.

> And queue reset is the perfect example showed that.
> Who ever implements the device should be ready to handle queue_enable writes after DRIVER_OK stage, it is really that simple.
> There is no need of new feature bit.

Hard to change the past, we didn't ask people to do it.

> > It would be great for me if we agree the device must support it, but maybe it is
> > just too late for that.
> Device must support it. There is nothing late about it.
> And if you are considering LM flow, then for sure it is not late because LM is just not fully baked.

Considering regular use, no LM.

-- 
MST