From patchwork Tue Feb 16 17:28:58 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 8329741 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 33C2F9F399 for ; Tue, 16 Feb 2016 17:29:22 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5915920272 for ; Tue, 16 Feb 2016 17:29:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5192620254 for ; Tue, 16 Feb 2016 17:29:19 +0000 (UTC) Received: from localhost ([::1]:48649 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVjR8-0001wY-Cs for patchwork-qemu-devel@patchwork.kernel.org; Tue, 16 Feb 2016 12:29:18 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33673) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVjR0-0001vm-Cf for qemu-devel@nongnu.org; Tue, 16 Feb 2016 12:29:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aVjQz-0004de-4w for qemu-devel@nongnu.org; Tue, 16 Feb 2016 12:29:10 -0500 Received: from mnementh.archaic.org.uk ([2001:8b0:1d0::1]:57390) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aVjQy-0004a4-R7 for qemu-devel@nongnu.org; Tue, 16 Feb 2016 12:29:09 -0500 Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.84) (envelope-from ) id 1aVjQo-0001aQ-Mb; Tue, 16 Feb 2016 17:28:58 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Date: Tue, 16 Feb 2016 17:28:58 +0000 Message-Id: <1455643738-6068-1-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 2.1.4 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:8b0:1d0::1 Cc: patches@linaro.org, Stefan Hajnoczi , Paolo Bonzini , Laszlo Ersek Subject: [Qemu-devel] [PATCH v2] qemu-options.hx: Improve documentation of chardev multiplexing mode X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The current documentation of chardev mux=on is rather brief and opaque; expand it to hopefully be a bit more helpful. Signed-off-by: Peter Maydell Reviewed-by: Laszlo Ersek Reviewed-by: Kashyap Chamarthy Reviewed-by: Stefan Hajnoczi --- There was some discussion on #qemu yesterday evening about multiplexing, and "make the docs a bit less confusing" was one suggestion... v1->v2 changes: * include examples of the multiplexer use * mention that some other command options implicitly create a mux * link to the documentation of the mux's escape keys * fix up the documentation of mux escape keys so it can actually be linked to * drop the not-implemented "Ctrl-a ?" from the docs * improve the documentation of the mux keys a bit (in particular mentioning -echr, and being more generic than just "console/monitor") Our doc structure overall is pretty busted (why is all the documentation of generic stuff like -chardev lurking in "PC system emulation", for instance), so this is about as far as I want to go in cleaning up for now... qemu-doc.texi | 30 ++++++++++++++++++++---------- qemu-options.hx | 45 +++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 63 insertions(+), 12 deletions(-) diff --git a/qemu-doc.texi b/qemu-doc.texi index c324da8..bc9dd13 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -158,7 +158,8 @@ TODO (no longer available) * pcsys_introduction:: Introduction * pcsys_quickstart:: Quick Start * sec_invocation:: Invocation -* pcsys_keys:: Keys +* pcsys_keys:: Keys in the graphical frontends +* mux_keys:: Keys in the character backend multiplexer * pcsys_monitor:: QEMU Monitor * disk_images:: Disk Images * pcsys_network:: Network emulation @@ -272,7 +273,7 @@ targets do not need a disk image. @c man end @node pcsys_keys -@section Keys +@section Keys in the graphical frontends @c man begin OPTIONS @@ -322,15 +323,23 @@ Toggle mouse and keyboard grab. In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down}, @key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log. -@kindex Ctrl-a h -During emulation, if you are using the @option{-nographic} option, use -@key{Ctrl-a h} to get terminal commands: +@c man end + +@node mux_keys +@section Keys in the character backend multiplexer + +@c man begin OPTIONS + +During emulation, if you are using a character backend multiplexer +(which is the default if you are using @option{-nographic}) then +several commands are available via an escape sequence. These +key sequences all start with an escape character, which is @key{Ctrl-a} +by default, but can be changed with @option{-echr}. The list below assumes +you're using the default. @table @key @item Ctrl-a h @kindex Ctrl-a h -@item Ctrl-a ? -@kindex Ctrl-a ? Print this help @item Ctrl-a x @kindex Ctrl-a x @@ -346,10 +355,11 @@ Toggle console timestamps Send break (magic sysrq in Linux) @item Ctrl-a c @kindex Ctrl-a c -Switch between console and monitor +Rotate between the frontends connected to the multiplexer (usually +this switches between the monitor and the console) @item Ctrl-a Ctrl-a -@kindex Ctrl-a a -Send Ctrl-a +@kindex Ctrl-a Ctrl-a +Send the escape character to the frontend @end table @c man end diff --git a/qemu-options.hx b/qemu-options.hx index 2f0465e..7e6762e 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -2162,8 +2162,49 @@ All devices must have an id, which can be any string up to 127 characters long. It is used to uniquely identify this device in other command line directives. A character device may be used in multiplexing mode by multiple front-ends. -The key sequence of @key{Control-a} and @key{c} will rotate the input focus -between attached front-ends. Specify @option{mux=on} to enable this mode. +Specify @option{mux=on} to enable this mode. +A multiplexer is a "1:N" device, and here the "1" end is your specified chardev +backend, and the "N" end is the various parts of QEMU that can talk to a chardev. +If you create a chardev with @option{id=myid} and @option{mux=on}, QEMU will +create a multiplexer with your specified ID, and you can then configure multiple +front ends to use that chardev ID for their input/output. Up to four different +front ends can be connected to a single multiplexed chardev. (Without +multiplexing enabled, a chardev can only be used by a single front end.) +For instance you could use this to allow a single stdio chardev to be used by +two serial ports and the QEMU monitor: + +@example +-chardev stdio,mux=on,id=char0 \ +-mon chardev=char0,mode=readline,default \ +-serial chardev:char0 \ +-serial chardev:char0 +@end example + +You can have more than one multiplexer in a system configuration; for instance +you could have a TCP port multiplexed between UART 0 and UART 1, and stdio +multiplexed between the QEMU monitor and a parallel port: + +@example +-chardev stdio,mux=on,id=char0 \ +-mon chardev=char0,mode=readline,default \ +-parallel chardev:char0 \ +-chardev tcp,...,mux=on,id=char1 \ +-serial chardev:char1 \ +-serial chardev:char1 +@end example + +When you're using a multiplexed character device, some escape sequences are +interpreted in the input. @xref{mux_keys, Keys in the character backend +multiplexer}. + +Note that some other command line options may implicitly create multiplexed +character backends; for instance @option{-serial mon:stdio} creates a +multiplexed stdio backend connected to the serial port and the QEMU monitor, +and @option{-nographic} also multiplexes the console and the monitor to +stdio. + +There is currently no support for multiplexing in the other direction +(where a single QEMU front end takes input and output from multiple chardevs). Every backend supports the @option{logfile} option, which supplies the path to a file to record all data transmitted via the backend. The @option{logappend}