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bh=0a/PVwf8mT84SctdYRE/NRCSd06QWazrC3sTRrW+jbA=; b=m+kfWf8Fmc+F9I6ZvhT8hEmAXGV/5oocj1zoFoWvITNSKQ6s0sGpPa5pBSFpc8SC/Yr5NK kTma2a6r/9gZNiDg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 6072E1394A; Thu, 7 Nov 2024 12:11:17 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id twQHCmWuLGdiLAAAD6G6ig (envelope-from ); Thu, 07 Nov 2024 12:11:17 +0000 From: Fabiano Rosas To: Prasad Pandit Cc: Peter Xu , qemu-devel@nongnu.org, Prasad Pandit Subject: Re: [PATCH 2/5] migration/postcopy: magic value for postcopy channel In-Reply-To: References: <20241029150908.1136894-1-ppandit@redhat.com> <20241029150908.1136894-3-ppandit@redhat.com> <87ldxw1p8k.fsf@suse.de> Date: Thu, 07 Nov 2024 09:11:14 -0300 Message-ID: <87ttcj2qhp.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: DFFBA1F8CC X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; ARC_NA(0.00)[]; ASN(0.00)[asn:25478, ipnet:::/0, country:RU]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCPT_COUNT_THREE(0.00)[4]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:dkim,suse.de:mid]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action Received-SPF: pass client-ip=195.135.223.131; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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 Prasad Pandit writes: > On Wed, 6 Nov 2024 at 18:41, Fabiano Rosas wrote: >> What we're thinking is having an initial exchange of information between >> src & dst as soon as migration starts and that would sync the >> capabilities and parameters between both sides. Which would then be >> followed by a channel establishment phase that would open each necessary >> channel (according to caps) in order, removing the current ambiguity. >> > > * Isn't that how it works? IIUC, libvirtd(8) sends migration command > options to the destination and based on that the destination prepares > for the multifd and/or postcopy migration. In case of 'Postcopy' the > source sends 'postcopy advise' to the destination to indicate that > postcopy might follow at the end of precopy. Also, in the discussion > above Peter mentioned that libvirtd(8) may exchange list of features > between source and destination to facilitate QMP clients. > > * What is the handshake doing differently? (just trying to understand) The handshake will be a QEMU-only feature. Libvirt will then only start the migration on src and QEMU will do the capabilities handling. > > Thank you. > --- > - Prasad