From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4510BCAC599 for ; Tue, 16 Sep 2025 13:08:50 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uyVPT-0002tF-U5; Tue, 16 Sep 2025 09:07:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uyVPG-0002o4-CC for qemu-devel@nongnu.org; Tue, 16 Sep 2025 09:07:40 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uyVPC-0005Qa-Cf for qemu-devel@nongnu.org; Tue, 16 Sep 2025 09:07:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758028050; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0OFRJGRY2omarrlZ0FW+w2RUI60hO9WGSthtqLUJYU4=; b=c1XJEZrh2dvOt5QiUEKKYxCU+AX5qn9y7F5KraX+0HDkH42509J6TnTkpFqKVHBebEbpTf EQL2SjIdwrKTnrNq1mgQiPL/afw9eW+uufGo1YalzVdt6curq4D4yzPqxJV/JOSHlDMD4d GsCloIMnYd+uVgdT0lTFJjV+oCvysK8= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-515-NBQZHE5OMkSP8lD4uTSKaA-1; Tue, 16 Sep 2025 09:07:27 -0400 X-MC-Unique: NBQZHE5OMkSP8lD4uTSKaA-1 X-Mimecast-MFC-AGG-ID: NBQZHE5OMkSP8lD4uTSKaA_1758028045 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6E8841955F27; Tue, 16 Sep 2025 13:07:25 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.9]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 54B161800447; Tue, 16 Sep 2025 13:07:24 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 1D6BA21E6A27; Tue, 16 Sep 2025 15:07:21 +0200 (CEST) From: Markus Armbruster To: Filip Hejsek Cc: Markus Armbruster , qemu-devel@nongnu.org, =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Paolo Bonzini , "Michael S. Tsirkin" , Laurent Vivier , Amit Shah , Eric Blake , Eduardo Habkost , Marcel Apfelbaum , Philippe =?utf-8?Q?Mathieu-Daud?= =?utf-8?Q?=C3=A9?= , Yanan Wang , Zhao Liu , Szymon Lukasz , Daniel =?utf-8?Q?P=2EBerrang=C3=A9?= , devel@lists.libvirt.org Subject: Re: [PATCH v4 07/10] qmp: add chardev-resize command In-Reply-To: (Filip Hejsek's message of "Tue, 16 Sep 2025 00:22:43 +0200") 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> Date: Tue, 16 Sep 2025 15:07:21 +0200 Message-ID: <87bjnao8ae.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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=-0.009, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Filip Hejsek writes: > 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 t= he >> > > > 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 c= onsole >> > > > 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..6e3ade98614c949be8= 041ec5905a490ff536dee9 100644 >> > > > --- a/chardev/char.c >> > > > +++ b/chardev/char.c >> > > > @@ -1269,6 +1269,20 @@ bool qmp_add_client_char(int fd, bool has_s= kipauth, bool skipauth, >> > > > return true; >> > > > } >> > > >=20=20 >> > > > +void qmp_chardev_resize(const char *id, uint16_t cols, uint16_t r= ows, >> > > > + 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), retu= rn >> > > > * the GSource object created. Please use this to add timeout hoo= k for >> > > > diff --git a/qapi/char.json b/qapi/char.json >> > > > index f0a53f742c8bee24c377551803a864fd36ac78cf..0a26c5eee6b71bc5de= 127a91b253cc69a9fe8ce6 100644 >> > > > --- a/qapi/char.json >> > > > +++ b/qapi/char.json >> > > > @@ -874,6 +874,28 @@ >> > > > { 'command': 'chardev-send-break', >> > > > 'data': { 'id': 'str' } } >> > > >=20=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. Double-checking: the command works for any ChardevBackendKind, doesn't it? > 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. I think I'd prefer "window" or "terminal". "resize" and "set size" suggest that the command initiates a size change. Not true, it notifies of a size change. Maybe "chardev-window-size-changed", "chardev-terminal-size-changed", "chardev-window-resized", or "chardev-terminal-resized". >> > > > +# >> > > > +# Notifies a chardev about the current size of the terminal conne= cted >> > > > +# 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 informat= ion >> > > 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 Another question... 'vc' chardevs accept optional @rows, @cols (see ChardevVC). Is this the same size or something else? >> 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. How does 0 x 0 behave compared to a valid size like 80 x 24? > 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. I think the QAPI schema doc comment is as good a place as any. >> > > 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. We have query-chardev. It doesn't return much. >> > > > +# >> > > > +# 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: >> > > > #