RE: [virtio-comment] RE: [PATCH v19] virtio-net: support inner header hash

[Parav Pandit <parav@nvidia.com>]

> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Wednesday, June 28, 2023 1:24 PM


> > Because when device has two ways to access config space, it always have to
> account and build the interface that, hey some driver will not use DMA.
> > Hence have it always in the MMIO accessible area.
> 
> Maybe I get it. You want to use the new features as a carrot to force drivers to
> implement DMA? You suspect they will ignore the spec requirement just
> because things seem to work?
>
Right because it is not a must normative.
 
> There's some logic here, for sure. you just might be right.
> 
> However, surely we can discuss this small tweak in 1.4 timeframe?

Sure, if we prefer the DMA approach I don't have a problem in adding temporary one field to config space.

I propose to add a line to the spec " Device Configuration Space" section, something like,

Note: Any new device configuration space fields additional MUST consider accessing such fields via a DMA interface.

And this will guide the new patches of what to do instead of last moment rush.