Re: [virtio-comment] Re: [PATCH v1 3/8] device-context: Define the device context fields for device migration

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

On Wed, Oct 25, 2023 at 10:22:03AM +0000, Parav Pandit wrote:
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Wednesday, October 25, 2023 3:50 PM
> > 
> > On Wed, Oct 25, 2023 at 09:50:02AM +0000, Parav Pandit wrote:
> > > Hence, I believe device context as defined now is still reusable as common
> > building block.
> > > For non-passthrough, such hypervisor can simply ignore the fields which it is
> > not interested in.
> > 
> > Interesting. So a hypervisor encounters a field it does not recognize. How does
> > hypervisor know that a field is safe to ignore?
> 
> In v2 all the supported fields are published in a query command.
> If hypervisor wants to know the precise fields of interest, when the device reports unknown field, it can make its decision to ignore or fail to work.

It really can't make any decisions here. Some fields are safe to ignore,
some are not but how can you tell?

-- 
MST