Re: [virtio-comment] Re: [virtio] RE: [virtio-comment] proposal: use admin command (and aq) of the device to query config space

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

On Wed, Aug 02, 2023 at 11:56:11AM +0000, Parav Pandit wrote:
> 
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Wednesday, August 2, 2023 5:21 PM
> 
> > 
> > There's one thing to say about putting everything in one place, and that is that
> > one can then find everything in one place.
> 
> When a device grows incrementally and each functionality also, 
> grouping it per functionality gives better pace to keep things self-contained.
> 
> Think how messy a set command would be if all 3 functionality in one set command.
> 
> > For example, at the moment we actually do have a problem with cvq, and the
> > problem is that it sets internal device state that is not observable (unlike original
> > pre-1.0 config space which was writeable).
> > 
> Which part is not observable?

e.g. rss config.

> > 
> > By the way there's a pci express ECN for relaxed ordering or something like this.
> > I am yet to look at it, I wonder whether it can be used to avoid the issues we
> > have with MMIO in a way that is easier to use than DMA.
> 
> Waiting to deliver new features on new PCI standard will drastically slow down virtio.

features? surely not. but when we are building a new transport then
we are building for the future, it takes years for a new
transport to be deployed.

> I don't think its good idea, but I would like to know about such ECN, if there is one.

I am talking about unordered IO (UIO) ECN.