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[79.176.118.93]) by smtp.gmail.com with ESMTPSA id u6sm1146290wmj.40.2020.11.03.23.42.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2020 23:43:01 -0800 (PST) Date: Wed, 4 Nov 2020 02:42:56 -0500 From: "Michael S. Tsirkin" To: Gerd Hoffmann Subject: Re: Out-of-Process Device Emulation session at KVM Forum 2020 Message-ID: <20201104024052-mutt-send-email-mst@kernel.org> References: <04179584-3324-994e-d793-04be18d2dab2@redhat.com> <95432b0c-919f-3868-b3f5-fc45a1eef721@redhat.com> <1cf6b664-63cc-7b57-0a2c-4d4f979d4950@redhat.com> <20201102101308.GA42093@stefanha-x1.localdomain> <20201104065052.hrc2entvg7bkodb6@sirius.home.kraxel.org> MIME-Version: 1.0 In-Reply-To: <20201104065052.hrc2entvg7bkodb6@sirius.home.kraxel.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/03 00:03:41 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H4=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Elena Ufimtseva , Janosch Frank , John G Johnson , Stefan Hajnoczi , Jason Wang , qemu-devel , Kirti Wankhede , Yan Vugenfirer , Jag Raman , Eugenio =?iso-8859-1?Q?P=E9rez?= , Anup Patel , Claudio Imbrenda , Christian Borntraeger , Roman Kagan , Felipe Franciosi , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Jens Freimann , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Stefano Garzarella , Eduardo Habkost , Sergio Lopez , Kashyap Chamarthy , Darren Kenny , Alex Williamson , Liran Alon , Stefan Hajnoczi , Thanos Makatos , Alex =?iso-8859-1?Q?Benn=E9e?= , David Gibson , Kevin Wolf , Halil Pasic , "Daniel P. Berrange" , Christophe de Dinechin , Paolo Bonzini , fam Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Nov 04, 2020 at 07:50:52AM +0100, Gerd Hoffmann wrote: > Hi, > > > > I think not. Obviously each firmware should have its own ABI no matter > > > whether its public or proprietary. For proprietary firmware, it should > > > be understood by the proprietary userspace counterpart. > > > > Userspace does not necessarily need to interpret the contents. The > > vendor can ship a binary blob and the driver loads the file onto the > > device without interpreting it. > > Exactly. Neither userspace nor kernel look at the blob, except maybe > some headers with version, size, checksum etc. Only the device does > something with the actual content. > > Doing the same make sense for migration device state. The kernel driver > saves and restores the device state. Userspace doesn't need to look at > it. Again, with an exception for some header fields. > > So requiring userspace being able to interpret the migration data > (except header) for all devices looks rather pointless to me. If nothing else we need a good place where vendors can publish this data. > Speaking of headers: Defining a common header format makes sense. > For standard devices (virtio, nvme, ...) it makes sense to try define > a standard, cross-vendor migration data format. > For vendor-specific devices (gpus for example) I absolutely don't see > the point. > > take care, > Gerd