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Tsirkin" Cc: Peter Xu , =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Thomas Huth , Yuri Benditovich , 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 , devel@lists.libvirt.org References: <39a8bb8b-4191-4f41-aaf7-06df24bf3280@daynix.com> <8ad96f43-83ae-49ae-abc1-1e17ee15f24d@daynix.com> <20240805032937-mutt-send-email-mst@kernel.org> Content-Language: en-US From: Akihiko Odaki In-Reply-To: <20240805032937-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: none client-ip=2607:f8b0:4864:20::230; envelope-from=akihiko.odaki@daynix.com; helo=mail-oi1-x230.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2024/08/05 16:30, Michael S. Tsirkin wrote: > On Sun, Aug 04, 2024 at 03:49:45PM +0900, Akihiko Odaki wrote: >> I suggest disabling all offload features of virtio-net with 9.2. > > Yea ... no. > >> I want to keep things consistent so I want to disable all at once. This >> change will be very uncomfortable for us, who are implementing offload >> features, but I hope it will motivate us to implement a proper solution. > > It's uncomfortable for users. An obvious alternative is to set cross-migrate=off by default (I dropped the no- prefix because no-cross-migrate=off is confusing). I don't have a particular idea whether cross-migrate should be on or off by default. This is a trade-off of safety and performance. In general, I believe safety should come first before performance. On the other hand, disabling offload features is a breaking change. QEMU also has -only-migratable option; it is more consistent to make the additional assurance for migration opt-in instead of opt-out. Finally, I see migration across hosts as an advanced feature, and perhaps it can be justified to make it more like an optional feature. Regards, Akihiko Odaki