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Wed, 17 Sep 2025 13:32:08 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.195]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 78912300018D; Wed, 17 Sep 2025 13:32:01 +0000 (UTC) Date: Wed, 17 Sep 2025 14:31:57 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Filip Hejsek Cc: Maximilian Immanuel Brandtner , amit@kernel.org, armbru@redhat.com, eblake@redhat.com, eduardo@habkost.net, lvivier@redhat.com, marcandre.lureau@redhat.com, marcel.apfelbaum@gmail.com, mst@redhat.com, noh4hss@gmail.com, pbonzini@redhat.com, philmd@linaro.org, qemu-devel@nongnu.org, wangyanan55@huawei.com, zhao1.liu@intel.com, nsg@linux.ibm.com Subject: Re: [PATCH v2] char-pty: add support for the terminal size Message-ID: References: <20250915162535.147642-1-maxbr@linux.ibm.com> <20250915163415.149190-1-maxbr@linux.ibm.com> <4c8e1ae5dd16d6ee4bcb42ed25d2987bc2c4a3cc.camel@gmail.com> <95142e7fd2a103cfb8d8bea9727117bfe952baec.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Sep 17, 2025 at 03:09:50PM +0200, Filip Hejsek wrote: > > > On September 17, 2025 11:39:55 AM GMT+02:00, Maximilian Immanuel Brandtner wrote: > > On Tue, 2025-09-16 at 00:02 +0200, Filip Hejsek wrote: > > > On Mon, 2025-09-15 at 18:34 +0200, Maximilian Immanuel Brandtner > > > wrote: > > > > Update the terminal size upon SIGWINCH delivery. > > > > > > > > Signed-off-by: Maximilian Immanuel Brandtner > > > > > > I don't think this will work, because SIGWINCH is only delivered for > > > the process' controling terminal. Unfortunately I don't think there > > > is > > > any way to get size notifications for arbitrary terminal. > > > > In that case there are two solutions: > > 1. make qemu the controlling process of the pty (this has the > > disadvantage of QEMU being quit when the pty is closed) > > A bigger disadvantage is that a process can only have one controlling terminal, and a terminal can only be the controlling terminal for a single session (and only sends signals to the foreground process group of that session). It would require forking a process for each pty, and I don't even know if the master end can have its own session. > > > 2. create a timer polling every eg 100ms to check if the winsize has > > changed > > > > I would go with the second approach then > > Me too, the timer is a bit unfortunate, but it's probably the less bad option. I don't think we want a timer polling for an situation that will very rarely arise. We already add the 'chardev_resize' QMP command, which is a good enough way to kick QEMU to re-read the size. With 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 :|