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 3387EC021AA for ; Tue, 18 Feb 2025 07:55:30 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tkIRe-00026V-QQ; Tue, 18 Feb 2025 02:55:06 -0500 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 1tkIRc-00023g-8f for qemu-devel@nongnu.org; Tue, 18 Feb 2025 02:55:04 -0500 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 1tkIRa-0006hV-6f for qemu-devel@nongnu.org; Tue, 18 Feb 2025 02:55:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739865300; 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=h/mw942lI/lMgagmUlGMvzED3dh1JnOW4dEURYgVbp8=; b=S3aiX6GqrMMAW5q4QrZGv1mDLrbh+MS5u1IghybHMZ4wcEXr4eJwLqNTIZ+G/YEEFeG/QC XqmK/BlwexmNCJCL9W/LTJZQjCkCzUiQyNOCFeegPL5VDMDvDODnxZPFZj34Iqxnkz9qM4 DNz43AX0NF7Ay05vDcAL2C63jhvnZJQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-497-1nbVj7EYO4ur_01WWZS-1w-1; Tue, 18 Feb 2025 02:54:56 -0500 X-MC-Unique: 1nbVj7EYO4ur_01WWZS-1w-1 X-Mimecast-MFC-AGG-ID: 1nbVj7EYO4ur_01WWZS-1w_1739865296 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F11651801A20; Tue, 18 Feb 2025 07:54:55 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.22]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A4AA419560AA; Tue, 18 Feb 2025 07:54:54 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 386F621E6A28; Tue, 18 Feb 2025 08:54:52 +0100 (CET) From: Markus Armbruster To: Roman Penyaev Cc: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , qemu-devel@nongnu.org Subject: Re: [PATCH v9 2/4] chardev/char-hub: implement backend chardev aggregator In-Reply-To: <20250123085327.965501-3-r.peniaev@gmail.com> (Roman Penyaev's message of "Thu, 23 Jan 2025 09:53:22 +0100") References: <20250123085327.965501-1-r.peniaev@gmail.com> <20250123085327.965501-3-r.peniaev@gmail.com> Date: Tue, 18 Feb 2025 08:54:52 +0100 Message-ID: <87eczvhelv.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 3.0 on 10.30.177.40 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=-0.001, 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_NONE=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 Roman Penyaev writes: > This patch implements a new chardev backend `hub` device, which > aggregates input from multiple backend devices and forwards it to a > single frontend device. Additionally, `hub` device takes the output > from the frontend device and sends it back to all the connected > backend devices. This allows for seamless interaction between > different backend devices and a single frontend interface. > > The idea of the change is trivial: keep list of backend devices > (up to 4), init them on demand and forward data buffer back and > forth. > > The following is QEMU command line example: > > -chardev pty,path=3D/tmp/pty,id=3Dpty0 \ > -chardev vc,id=3Dvc0 \ > -chardev hub,id=3Dhub0,chardevs.0=3Dpty0,chardevs.1=3Dvc0 \ > -device virtconsole,chardev=3Dhub0 \ > -vnc 0.0.0.0:0 > > Which creates 2 backend devices: text virtual console (`vc0`) and a > pseudo TTY (`pty0`) connected to the single virtio hvc console with > the backend aggregator (`hub0`) help. `vc0` renders text to an image, > which can be shared over the VNC protocol. `pty0` is a pseudo TTY > backend which provides biderectional communication to the virtio hvc > console. > > 'chardevs.N' list syntax is used for the sake of compatibility with > the representation of JSON lists in 'key=3Dval' pairs format of the > util/keyval.c, despite the fact that modern QAPI way of parsing, > namely qobject_input_visitor_new_str(), is not used. Choice of keeping > QAPI list syntax may help to smoothly switch to modern parsing in the > future. > > Signed-off-by: Roman Penyaev > Reviewed-by: "Marc-Andr=C3=A9 Lureau" > Cc: qemu-devel@nongnu.org [...] > diff --git a/qapi/char.json b/qapi/char.json > index e04535435034..f02b66c06b3e 100644 > --- a/qapi/char.json > +++ b/qapi/char.json > @@ -332,6 +332,19 @@ > 'data': { 'chardev': 'str' }, > 'base': 'ChardevCommon' } >=20=20 > +## > +# @ChardevHub: > +# > +# Configuration info for hub chardevs. > +# > +# @chardevs: List of chardev IDs, which should be added to this hub Suggest "IDs to be added". According to the commit message, there's a limit of four chardevs. Better document that here. > +# > +# Since: 10.0 > +## > +{ 'struct': 'ChardevHub', > + 'data': { 'chardevs': ['str'] }, > + 'base': 'ChardevCommon' } > + > ## > # @ChardevStdio: > # > @@ -479,6 +492,8 @@ > # > # @mux: (since 1.5) > # > +# @hub: (since 10.0) > +# > # @msmouse: emulated Microsoft serial mouse (since 1.5) > # > # @wctablet: emulated Wacom Penpartner serial tablet (since 2.9) > @@ -521,6 +536,7 @@ > 'pty', > 'null', > 'mux', > + 'hub', > 'msmouse', > 'wctablet', > { 'name': 'braille', 'if': 'CONFIG_BRLAPI' }, > @@ -595,6 +611,16 @@ > { 'struct': 'ChardevMuxWrapper', > 'data': { 'data': 'ChardevMux' } } >=20=20 > +## > +# @ChardevHubWrapper: > +# > +# @data: Configuration info for hub chardevs > +# > +# Since: 10.0 > +## > +{ 'struct': 'ChardevHubWrapper', > + 'data': { 'data': 'ChardevHub' } } > + > ## > # @ChardevStdioWrapper: > # > @@ -703,6 +729,7 @@ > 'pty': 'ChardevPtyWrapper', > 'null': 'ChardevCommonWrapper', > 'mux': 'ChardevMuxWrapper', > + 'hub': 'ChardevHubWrapper', > 'msmouse': 'ChardevCommonWrapper', > 'wctablet': 'ChardevCommonWrapper', > 'braille': { 'type': 'ChardevCommonWrapper', With the doc nits addressed Acked-by: Markus Armbruster