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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Akihiko Odaki <akihiko.odaki@daynix.com>
Cc: "Peter Xu" <peterx@redhat.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Thomas Huth" <thuth@redhat.com>,
	"Yuri Benditovich" <yuri.benditovich@daynix.com>,
	eduardo@habkost.net, marcel.apfelbaum@gmail.com,
	philmd@linaro.org, wangyanan55@huawei.com,
	dmitry.fleytman@gmail.com, jasowang@redhat.com,
	sriram.yagnaraman@est.tech, sw@weilnetz.de,
	qemu-devel@nongnu.org, yan@daynix.com,
	"Fabiano Rosas" <farosas@suse.de>,
	devel@lists.libvirt.org
Subject: Re: [PATCH v2 4/4] virtio-net: Add support for USO features
Date: Thu, 8 Aug 2024 06:54:46 -0400	[thread overview]
Message-ID: <20240808065339-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <890f9d0a-3ded-488d-b274-8be9c38b5df3@daynix.com>

On Thu, Aug 08, 2024 at 07:52:37PM +0900, Akihiko Odaki wrote:
> On 2024/08/06 22:29, Michael S. Tsirkin wrote:
> > 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.
> 
> We can do nothing in such a case. Whether it is on a single host or multiple
> hosts, we cannot support migration if features once enabled disappear.
> 
> Regards,
> Akihiko Odaki

It does not follow that we have to do something, and this is something,
therefore that we have to do this.

This is just a reason not to handle checkpoint/restart any different
than any other migration.

-- 
MST



  reply	other threads:[~2024-08-08 10:55 UTC|newest]

Thread overview: 107+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-31 22:31 [PATCH v2 0/4] virtio-net: add USO feature (UDP segmentation offload) Yuri Benditovich
2023-07-31 22:31 ` [PATCH v2 1/4] tap: Add USO support to tap device Yuri Benditovich
2023-07-31 22:31 ` [PATCH v2 2/4] tap: Add check for USO features Yuri Benditovich
2023-07-31 22:31 ` [PATCH v2 3/4] virtio-net: Add USO flags to vhost support Yuri Benditovich
2023-07-31 22:31 ` [PATCH v2 4/4] virtio-net: Add support for USO features Yuri Benditovich
2023-08-02  5:17   ` Akihiko Odaki
2024-07-25 22:18   ` Peter Xu
2024-07-26  2:12     ` Jason Wang
2024-07-26 15:01       ` Peter Xu
2024-07-26  6:08     ` Michael S. Tsirkin
2024-07-26  7:03       ` Thomas Huth
2024-07-26  7:25         ` Michael S. Tsirkin
2024-07-26 11:32           ` Peter Xu
2024-07-26 17:39           ` Thomas Huth
2024-07-26 20:55             ` Peter Xu
2024-08-01  5:41             ` Michael S. Tsirkin
2024-07-26  8:48         ` Daniel P. Berrangé
2024-07-26 14:43           ` Peter Xu
2024-07-26 15:17             ` Daniel P. Berrangé
2024-07-26 20:47               ` Peter Xu
2024-07-28 15:18                 ` Akihiko Odaki
2024-07-29  3:50                   ` Jason Wang
2024-07-29  4:45                     ` Akihiko Odaki
2024-07-29 14:29                       ` Peter Xu
2024-07-29 16:43                         ` Akihiko Odaki
2024-07-30  2:04                           ` Jason Wang
2024-07-30  2:57                             ` Akihiko Odaki
2024-07-30  3:03                               ` Jason Wang
2024-07-30  3:11                                 ` Akihiko Odaki
2024-07-30  3:17                                   ` Jason Wang
2024-07-30  3:28                                     ` Akihiko Odaki
2024-07-30  3:45                                       ` Jason Wang
2024-07-30 10:23                                         ` Akihiko Odaki
2024-07-30 11:52                                           ` Yuri Benditovich
2024-07-31  2:05                                           ` Jason Wang
2024-07-29 15:58                 ` Daniel P. Berrangé
2024-07-29 17:00                   ` Peter Xu
2024-07-29 17:23                     ` Akihiko Odaki
2024-07-30 18:02                       ` Peter Xu
2024-07-29 17:26                     ` Daniel P. Berrangé
2024-07-30 18:13                       ` Peter Xu
2024-07-30 18:46                         ` Daniel P. Berrangé
2024-07-30 19:11                           ` Peter Xu
2024-07-30 19:22                             ` Michael S. Tsirkin
2024-07-30 20:03                               ` Peter Xu
2024-07-30 21:32                                 ` Michael S. Tsirkin
2024-07-30 22:01                                   ` Peter Xu
2024-07-31  2:01                                   ` Jason Wang
2024-07-31  7:04                                   ` Daniel P. Berrangé
2024-07-31  7:41                                     ` Michael S. Tsirkin
2024-07-31 12:57                                       ` Peter Xu
2024-08-01  2:28                                         ` Jason Wang
2024-08-01  5:28                                           ` Akihiko Odaki
2024-08-01  5:34                                         ` Michael S. Tsirkin
2024-08-01  5:51                                         ` Michael S. Tsirkin
2024-08-01 15:36                                           ` Peter Xu
2024-08-01 15:39                                             ` Michael S. Tsirkin
2024-08-01 15:45                                           ` Daniel P. Berrangé
2024-08-01 15:50                                             ` Michael S. Tsirkin
2024-08-01 15:58                                               ` Daniel P. Berrangé
2024-08-01  5:05                             ` Akihiko Odaki
2024-08-01 15:13                               ` Peter Xu
2024-08-01 15:15                                 ` Michael S. Tsirkin
2024-08-01 15:25                                   ` Daniel P. Berrangé
2024-08-02  4:30                                 ` Akihiko Odaki
2024-08-02 13:21                                   ` Michael S. Tsirkin
2024-08-02 15:05                                   ` Peter Xu
2024-08-02 15:54                                     ` Akihiko Odaki
2024-08-02 16:26                                       ` Peter Xu
2024-08-02 16:40                                         ` Michael S. Tsirkin
2024-08-02 20:56                                           ` Peter Xu
2024-08-04  6:49                                         ` Akihiko Odaki
2024-08-04 13:08                                           ` Peter Xu
2024-08-04 13:41                                             ` Michael S. Tsirkin
2024-08-05  7:27                                             ` Akihiko Odaki
2024-08-06 20:41                                               ` Peter Xu
2024-08-08 11:43                                                 ` Akihiko Odaki
2024-08-08 13:55                                                   ` Peter Xu
2024-08-08 14:45                                                     ` Michael S. Tsirkin
2024-08-09 10:28                                                     ` Akihiko Odaki
2024-08-05  7:30                                           ` Michael S. Tsirkin
2024-08-05  7:53                                             ` Akihiko Odaki
2024-08-05  8:23                                               ` Michael S. Tsirkin
2024-08-05  9:37                                                 ` Akihiko Odaki
2024-08-05 10:08                                                   ` Michael S. Tsirkin
2024-08-06  7:35                                                     ` Akihiko Odaki
2024-08-06 13:29                                                       ` Michael S. Tsirkin
2024-08-08 10:52                                                         ` Akihiko Odaki
2024-08-08 10:54                                                           ` Michael S. Tsirkin [this message]
2024-08-08 11:03                                                             ` Akihiko Odaki
2024-08-08 11:12                                                               ` Michael S. Tsirkin
2024-08-08 11:32                                                                 ` Akihiko Odaki
2024-08-08 14:21                                                                   ` Peter Xu
2024-08-08 14:15                                                                 ` Peter Xu
2024-08-08 14:47                                                                   ` Michael S. Tsirkin
2024-08-08 15:25                                                                     ` Peter Xu
2024-08-09 12:50                                                                       ` Fabiano Rosas
2024-08-18  5:04                                                                         ` Akihiko Odaki
2024-08-18  7:03                                                                           ` Michael S. Tsirkin
2024-08-19  4:27                                                                             ` Akihiko Odaki
2024-08-11  7:35                                                                       ` Michael S. Tsirkin
2024-08-18  5:09                                                                       ` Akihiko Odaki
2024-07-29 17:02                   ` Akihiko Odaki
2024-08-01  5:38                     ` Michael S. Tsirkin
2024-07-29  3:52       ` Jason Wang
2023-08-09 20:21 ` [PATCH v2 0/4] virtio-net: add USO feature (UDP segmentation offload) Yuri Benditovich
2023-08-10  3:14   ` Jason Wang

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