[virtio-dev] Re: [virtio-comment] Re: [PATCH 09/11] transport-pci: Describe PCI MMR dev config registers

Jason Wang
2023-04-14T03:18:37Z

On Fri, Apr 14, 2023 at 11:13 AM Parav Pandit <parav@nvidia.com> wrote:
>
>
>
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Thursday, April 13, 2023 11:09 PM
>
> >
> > Actually not, I think I've mentioned the reason for several times:
> >
> > It's a must for ABI and migration compatibility:
> >
> > 1) The offset is not necessarily a page boundary
> > 2) The length is not necessarily times of a PAGE_SIZE
> > 3) PAGE_SIZE varies among different archs
> > 4) Two vendors may have two different layout for the structure
>
> Migration compatibility check and device composition work will start for regular PCI VF in virtio.
> Two vendors will had some level of programmability as well to make this happen.
> It is orthogonal topic.

Actually not, having new blockers for live migration will complicate
the solution in the future.

And 1) 2) 3) can happen even if we don't care about migration compatibility, no?

Thanks