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

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.