Roman Penyaev <r.peni...@gmail.com> writes: > This adds a few lines describing `hub` aggregator configuration > for aggregation of several backend devices with a single frontend > device. > > Signed-off-by: Roman Penyaev <r.peni...@gmail.com> > Cc: "Marc-André Lureau" <marcandre.lur...@redhat.com> > Cc: qemu-devel@nongnu.org > --- > qemu-options.hx | 48 ++++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 44 insertions(+), 4 deletions(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 7090d59f6f10..fdc46f7e68b3 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -3720,7 +3720,7 @@ SRST > The general form of a character device option is: > > ``-chardev backend,id=id[,mux=on|off][,options]`` > - Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, > + Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, ``hub``, > ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, > ``pty``, ``stdio``, ``braille``, ``parallel``, > ``spicevmc``, ``spiceport``. The specific backend will determine the > @@ -3777,9 +3777,10 @@ The general form of a character device option is: > the QEMU monitor, and ``-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). > + If you need to aggregate data in the opposite direction (where one > + QEMU frontend interface receives input and output from multiple > + backend chardev devices), please refer to the paragraph below > + regarding chardev ``hub`` aggregator device configuration. > > Every backend supports the ``logfile`` option, which supplies the > path to a file to record all data transmitted via the backend. The > @@ -3879,6 +3880,45 @@ The available backends are: > Forward QEMU's emulated msmouse events to the guest. ``msmouse`` > does not take any options. > > +``-chardev hub,id=id,chardevs.0=id[,chardevs.N=id]`` Explicitly create > + chardev backend hub device with the possibility to aggregate input > + from multiple backend devices and forward 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. Aggregation > + supported for up to 4 chardev devices. (Since 10.0) > + > + For example, the following is a use case of 2 backend devices: > + virtual console ``vc0`` and a pseudo TTY ``pty0`` connected to > + a single virtio hvc console frontend device with a hub ``hub0`` > + help. Virtual console renders text to an image, which can be > + shared over the VNC protocol. In turn, pty backend provides > + bidirectional communication to the virtio hvc console over the > + pseudo TTY file. The example configuration can be as follows: > + > + :: > + > + -chardev pty,path=/tmp/pty,id=pty0 \ > + -chardev vc,id=vc0 \ > + -chardev hub,id=hub0,chardevs.0=pty0,chardevs.1=vc0 \ > + -device virtconsole,chardev=hub0 \ > + -vnc 0.0.0.0:0 > + > + Once QEMU starts VNC client and any TTY emulator can be used to > + control a single hvc console: > + > + :: > + > + # Start TTY emulator > + tio /tmp/pty > + > + # Start VNC client and switch to virtual console Ctrl-Alt-2 > + vncviewer :0 > + > + Several frontend devices is not supported. Stacking of multiplexers > + and hub devices is not supported as well. > +
Not sure why this breaks but I'm seeing: FAILED: docs/docs.stamp /usr/bin/env CONFDIR=etc/qemu /home/alex/lsrc/qemu.git/builds/all/pyvenv/bin/sphinx-build -q -W -Dkerneldoc_werror=1 -j auto -Dversion=9.2.50 -Drelease= -Ddepfile=docs/docs.d -Ddepfile_stamp=docs/docs.stamp -b html -d /home/alex/lsrc/qemu.git/builds/all/docs/manual.p /home/alex/lsrc/qemu.git/docs /home/alex/lsrc/qemu.git/builds/all/docs/manual Warning, treated as error: /home/alex/lsrc/qemu.git/qemu-options.hx:3884:'any' reference target not found: hub > ``-chardev > vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` > Connect to a QEMU text console. ``vc`` may optionally be given a > specific size. -- Alex Bennée Virtualisation Tech Lead @ Linaro
