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[79.98.72.129]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b07b32f20dcsm1017713266b.90.2025.09.15.15.22.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Sep 2025 15:22:44 -0700 (PDT) Message-ID: Subject: Re: [PATCH v4 07/10] qmp: add chardev-resize command From: Filip Hejsek To: Markus Armbruster Cc: qemu-devel@nongnu.org, =?ISO-8859-1?Q?Marc-Andr=E9?= Lureau , Paolo Bonzini , "Michael S. Tsirkin" , Laurent Vivier , Amit Shah , 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=2EBerrang=E9?= , devel@lists.libvirt.org Date: Tue, 16 Sep 2025 00:22:43 +0200 In-Reply-To: <87cy7s1auw.fsf@pond.sub.org> References: <20250912-console-resize-v4-0-7925e444afc4@gmail.com> <20250912-console-resize-v4-7-7925e444afc4@gmail.com> <871pob7ot7.fsf@pond.sub.org> <64d6252959750b8da6f3bc4ac7c738b10463bf6d.camel@gmail.com> <87cy7s1auw.fsf@pond.sub.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::62c; envelope-from=filip.hejsek@gmail.com; helo=mail-ej1-x62c.google.com 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 Mon, 2025-09-15 at 08:35 +0200, Markus Armbruster wrote: > Filip Hejsek writes: >=20 > > On Fri, 2025-09-12 at 16:01 +0200, Markus Armbruster wrote: > > > Cc: libvirt > > >=20 > > > Filip Hejsek writes: > > >=20 > > > > From: Szymon Lukasz > > > >=20 > > > > The managment software can use this command to notify QEMU about th= e > > > > size of the terminal connected to a chardev, QEMU can then forward = this > > > > information to the guest if the chardev is connected to a virtio co= nsole > > > > device. > > > >=20 > > > > Signed-off-by: Szymon Lukasz > > > > Suggested-by: Daniel P. Berrang=C3=A9 > > > > Signed-off-by: Filip Hejsek > > > > --- > > > > chardev/char.c | 14 ++++++++++++++ > > > > qapi/char.json | 22 ++++++++++++++++++++++ > > > > 2 files changed, 36 insertions(+) > > > >=20 > > > > diff --git a/chardev/char.c b/chardev/char.c > > > > index b45d79cb9b57643827eb7479257fdda2cf6b0434..6e3ade98614c949be80= 41ec5905a490ff536dee9 100644 > > > > --- a/chardev/char.c > > > > +++ b/chardev/char.c > > > > @@ -1269,6 +1269,20 @@ bool qmp_add_client_char(int fd, bool has_sk= ipauth, bool skipauth, > > > > return true; > > > > } > > > > =20 > > > > +void qmp_chardev_resize(const char *id, uint16_t cols, uint16_t ro= ws, > > > > + Error **errp) > > > > +{ > > > > + Chardev *chr; > > > > + > > > > + chr =3D qemu_chr_find(id); > > > > + if (chr =3D=3D NULL) { > > > > + error_setg(errp, "Chardev '%s' not found", id); > > > > + return; > > > > + } > > > > + > > > > + qemu_chr_resize(chr, cols, rows); > > > > +} > > > > + > > > > /* > > > > * Add a timeout callback for the chardev (in milliseconds), retur= n > > > > * the GSource object created. Please use this to add timeout hook= for > > > > diff --git a/qapi/char.json b/qapi/char.json > > > > index f0a53f742c8bee24c377551803a864fd36ac78cf..0a26c5eee6b71bc5de1= 27a91b253cc69a9fe8ce6 100644 > > > > --- a/qapi/char.json > > > > +++ b/qapi/char.json > > > > @@ -874,6 +874,28 @@ > > > > { 'command': 'chardev-send-break', > > > > 'data': { 'id': 'str' } } > > > > =20 > > > > +## > > > > +# @chardev-resize: > > >=20 > > > This name doesn't tell me what is being resized. PATCH 04 uses > > > "winsize", which is better. The (losely) related SIGWINCH suggests > > > "window change" or "window size change". Below, you use "terminal > > > size". > >=20 > > How about chardev-console-resize? That would match the name of the > > virtio event (VIRTIO_CONSOLE_RESIZE). >=20 > Not bad. It could become slightly bad if we make devices other than > "consoles" make us of it. Would that be possible? I don't think the size has any meaning for devices that are not connected to a console, although the code does not care whether it actually is a console and simply has a size for every chardev. I guess I could also rename it to chardev-window-resize or chardev-set-window-size. Let me know if you prefer one of these. > > > > +# > > > > +# Notifies a chardev about the current size of the terminal connec= ted > > > > +# to this chardev. > > >=20 > > > Yes, but what is it good for? Your commit message tells: "managment > > > software can use this command to notify QEMU about the size of the > > > terminal connected to a chardev, QEMU can then forward this informati= on > > > to the guest if the chardev is connected to a virtio console device." > >=20 > > How about: > >=20 > > Notifies a chardev about the current size of the terminal connected > > to this chardev. The information will be forwarded to the guest if > > the chardev is connected to a virtio console device. >=20 > Works for me. >=20 > > > > +# > > > > +# @id: the chardev's ID, must exist > > > > +# @cols: the number of columns > > > > +# @rows: the number of rows > > >=20 > > > Blank lines between the argument descriptions, bease. > > >=20 > > > What's the initial size? > >=20 > > 0x0 >=20 > A clearly invalid size. I guess it effectively means "unknown size". > Should we document that? Probably. 0x0 is I think also the default size in the Linux kernel, but I don't think the Linux kernel documents this. Another question is if the 0x0 size should be propagated to the guest over virtio. I think it should be, although the virtio spec says nothing about 0x0 size. I'm not sure what is the right place to document this. > > > Do we need a way to query the size? > >=20 > > I don't think it is necessary. What would be the usecase for that? >=20 > I don't know, but it's my standard question when I see an interface to > set something without an interface to get it. Its purpose is to make us > think, not to make us at the get blindly. I guess it might be useful for debugging. If the size is not propagated correctly, one might query it to find out on which side the problem is. > > > > +# > > > > +# Since: 10.2 > > > > +# > > > > +# .. qmp-example:: > > > > +# > > > > +# -> { "execute": "chardev-resize", "arguments": { "id": "foo"= , "cols": 80, "rows": 24 } } > > > > +# <- { "return": {} } > > > > +## > > > > +{ 'command': 'chardev-resize', > > > > + 'data': { 'id': 'str', > > > > + 'cols': 'uint16', > > > > + 'rows': 'uint16' } } > > > > + > > > > ## > > > > # @VSERPORT_CHANGE: > > > > #