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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id ca18e2360f4ac-83503a74b7csm187106639f.9.2024.10.08.12.38.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Oct 2024 12:38:54 -0700 (PDT) Date: Tue, 8 Oct 2024 15:38:51 -0400 From: Peter Xu To: Steven Sistare Cc: qemu-devel@nongnu.org, Fabiano Rosas , David Hildenbrand , Marcel Apfelbaum , Eduardo Habkost , Philippe Mathieu-Daude , Paolo Bonzini , "Daniel P. Berrange" , Markus Armbruster Subject: Re: [PATCH V2 13/13] migration: cpr-transfer mode Message-ID: References: <1727725244-105198-1-git-send-email-steven.sistare@oracle.com> <1727725244-105198-14-git-send-email-steven.sistare@oracle.com> <5da33a31-bdcc-45ff-89c0-55b8ab08954b@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5da33a31-bdcc-45ff-89c0-55b8ab08954b@oracle.com> Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.151, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-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 Tue, Oct 08, 2024 at 03:12:32PM -0400, Steven Sistare wrote: > > This is slightly tricky part and would be nice to be documented somewhere, > > perhaps starting from in the commit message. > > I will extend the block comment in qmp_migrate: > > /* > * For cpr-transfer, the target may not be listening yet on the migration > * channel, because first it must finish cpr_load_state. The target tells > * us it is listening by closing the cpr-state socket. Wait for that HUP > * event before connecting in qmp_migrate_finish. > * > * The HUP could occur because the target fails while reading CPR state, > * in which case the target will not listen for the incoming migration > * connection, so qmp_migrate_finish will fail to connect, and then recover. > */ Yes this is better, thanks. > > > Then the error will say "failed to connect to destination QEMU" hiding the > > real failure (cpr save/load failed), right? That's slightly a pity. > > Yes, but destination qemu will also emit a more specific message. True. > > > I'm OK with the HUP as of now, but if you care about accurate CPR-stage > > error reporting, then feel free to draft something else in the next post. > > I'll think about it, but to get cpr into 9.2, this will probably need to be > deferred as a future enhancement. Yep that's OK. -- Peter Xu