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

[Parav Pandit <parav@nvidia.com>]

> 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?

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