Re: [PATCH v2 4/4] virtio-net: Add support for USO features

[Michael S. Tsirkin]

On Tue, Aug 06, 2024 at 04:35:44PM +0900, Akihiko Odaki wrote:
> On 2024/08/05 19:08, Michael S. Tsirkin wrote:
> > On Mon, Aug 05, 2024 at 06:37:58PM +0900, Akihiko Odaki wrote:
> > > If cross-migrate=off, QEMU can still migrate on the same host (checkpoint
> > > and restart). QEMU can also migrate across hosts if the user ensures they
> > > are on the same platform.
> > 
> > What is so special about checkpoint/restart? I guess we hope that
> > downgrades are uncommon, but they are possible...
> 
> Downgrades will not work with cross-migrate=off. Users who want downgrades
> should use cross-migrate=on.

We also don't know that upgrades do not disable a feature:
can happen if e.g. there's a serious bug in the feature.
Basically, this makes the feature too fragile, in my opinion.

-- 
MST