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Tsirkin" To: Filip Hejsek Cc: qemu-devel@nongnu.org, =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Paolo Bonzini , Laurent Vivier , Amit Shah , Markus Armbruster , Eric Blake , Eduardo Habkost , Marcel Apfelbaum , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Yanan Wang , Zhao Liu , Szymon Lukasz , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PATCH v4 00/10] virtio-console: notify about the terminal size Message-ID: <20250915190638-mutt-send-email-mst@kernel.org> References: <20250912-console-resize-v4-0-7925e444afc4@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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, Sep 16, 2025 at 01:02:02AM +0200, Filip Hejsek wrote: > While thinking about the patches, a few questions about the virtio spec > have popped into my head. > > 1. Should the config space size also be updated (for port 0) when > multiport is used? Based on my reading of the spec, I think yes. > > 2. Can VIRTIO_CONSOLE_RESIZE be sent if VIRTIO_CONSOLE_F_SIZE is not > negotiated? The spec does not say, which I think means it can. But the guest can't do anything useful here. > 3. The spec says that reading from config space fields that are > conditional on features should be allowed even if the driver has not > (yet) accepted the feature. Does it mean that we have to update the > size even if the feature is not accepted (yet), or is it OK if the > reads return 0? This is talking about the window before FEATURES_OK (and so DRIVER_OK) is set. It is best to update the size. There's no interrupt to send though. > Thanks for any answers or opinions, > Filip Hejsek