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[193.239.39.51]) by smtp.gmail.com with ESMTPSA id v22sm4722011ljg.12.2020.06.25.02.52.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2020 02:52:14 -0700 (PDT) Date: Thu, 25 Jun 2020 11:52:08 +0200 From: Szymon Lukasz To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PATCH v2 0/6] virtio-console: notify about the terminal size Message-ID: <20200625095208.GA118320@aorus> References: <20200624112640.82673-1-noh4hss@gmail.com> <20200624114915.GH774096@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200624114915.GH774096@redhat.com> Received-SPF: pass client-ip=2a00:1450:4864:20::142; envelope-from=noh4hss@gmail.com; helo=mail-lf1-x142.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: lvivier@redhat.com, mst@redhat.com, amit@kernel.org, qemu-devel@nongnu.org, pbonzini@redhat.com, marcandre.lureau@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 24, 2020 at 12:49:15PM +0100, Daniel P. Berrangé wrote: > On Wed, Jun 24, 2020 at 01:26:34PM +0200, Szymon Lukasz wrote: > > Also there is a problem with the virtio spec and Linux Kernel > > implementation, the order of fields in virtio_console_resize struct > > differs between the kernel and the spec. I do not know if there is any > > implementation of the virtio-console driver that handles resize messages > > and uses a different order than Linux. > > Well this is a bit of a mess :-( > > The main virtio_console_config struct has cols, then rows. > > The Linux impl of resizing appears to have arrived in 2010, and created > a new struct with rows, then cols. > > commit 8345adbf96fc1bde7d9846aadbe5af9b2ae90882 > Author: Amit Shah > Date: Thu May 6 02:05:09 2010 +0530 > > virtio: console: Accept console size along with resize control message > > The VIRTIO_CONSOLE_RESIZE control message sent to us by the host now > contains the new {rows, cols} values for the console. This ensures each > console port gets its own size, and we don't depend on the config-space > rows and cols values at all now. > > Signed-off-by: Amit Shah > CC: Christian Borntraeger > CC: linuxppc-dev@ozlabs.org > CC: Kusanagi Kouichi > Signed-off-by: Rusty Russell > > > The virtio spec documenting this came 4 years later in 2014 and documented > the resize struct with cols, then rows, which differs from Linux impl, > but matches ordering of the main virtio_console_config: > > commit 908cfaa782e950d6656d947599d7a6c9fb16cad1 > Author: rusty > Date: Wed Feb 12 03:15:57 2014 +0000 > > Feedback #6: Applied > > As per minutes: > https://lists.oasis-open.org/archives/virtio/201402/msg00121.html > > Signed-off-by: Rusty Russell > > git-svn-id: https://tools.oasis-open.org/version-control/svn/virtio@237 0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652 > > I can understand why it is desirable for the resize struct to match > the order of the initial config struct. I'm guessing it just wasn't > realized that the Linux impl was inverted for resize > > The FreeBSD impl of virtio-console doesn't do resize: > > https://github.com/freebsd/freebsd/blob/master/sys/dev/virtio/console/virtio_console.c#L874 > > Not sure what other impls are going to be around, but I feel like > Linux is going to be the most commonly deployed by orders of magnitude. > > So I'd say QEMU should match Linux, and the spec should be fixed. I had the same thoughts. I will ask for a change in the spec. > > > Have you reported this bug to the virtio spec people directly yet ? > > I don't see an issue open at > > https://github.com/oasis-tcs/virtio-spec/issues/ > > so I think one should be filed there > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| >