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.peniaev@gmail.com>
Cc: "Marc-André Lureau" <marcandre.lureau@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.
+
``-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.
--
2.43.0
Roman Penyaev <r.peniaev@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.peniaev@gmail.com> > Cc: "Marc-André Lureau" <marcandre.lureau@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
On Tue, Jan 21, 2025 at 4:02 PM Alex Bennée <alex.bennee@linaro.org> wrote:
>
> Roman Penyaev <r.peniaev@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.peniaev@gmail.com>
> > Cc: "Marc-André Lureau" <marcandre.lureau@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
This is odd, my make is silent. Can you please check this?
diff --git a/qemu-options.hx b/qemu-options.hx
index fdc46f7e68b3..e6d9de142aaf 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3880,7 +3880,8 @@ 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 hub,id=id,chardevs.0=id[,chardevs.N=id]``
+ Explicitly create
--
Roman
Roman Penyaev <r.peniaev@gmail.com> writes:
> On Tue, Jan 21, 2025 at 4:02 PM Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>> Roman Penyaev <r.peniaev@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.peniaev@gmail.com>
>> > Cc: "Marc-André Lureau" <marcandre.lureau@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
>
> This is odd, my make is silent. Can you please check this?
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index fdc46f7e68b3..e6d9de142aaf 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3880,7 +3880,8 @@ 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 hub,id=id,chardevs.0=id[,chardevs.N=id]``
> + Explicitly create
No joy. I did replicate from the command line and s/-q/-v/
writing output... [ 43%] specs/fsi .. specs/ppc-spapr-hotplug
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/sphinx/cmd/build.py", line 281, in build_main
app.build(args.force_all, args.filenames)
File "/usr/lib/python3/dist-packages/sphinx/application.py", line 341, in build
self.builder.build_update()
File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 310, in build_update
self.build(to_build,
File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 376, in build
self.write(docnames, list(updated_docnames), method)
File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 568, in write
self._write_parallel(sorted(docnames),
File "/usr/lib/python3/dist-packages/sphinx/builders/__init__.py", line 612, in _write_parallel
doctree = self.env.get_and_resolve_doctree(docname, self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3/dist-packages/sphinx/environment/__init__.py", line 591, in get_and_resolve_doctree
self.apply_post_transforms(doctree, docname)
File "/usr/lib/python3/dist-packages/sphinx/environment/__init__.py", line 637, in apply_post_transforms
transformer.apply_transforms()
File "/usr/lib/python3/dist-packages/sphinx/transforms/__init__.py", line 80, in apply_transforms
super().apply_transforms()
File "/usr/lib/python3/dist-packages/docutils/transforms/__init__.py", line 173, in apply_transforms
transform.apply(**kwargs)
File "/usr/lib/python3/dist-packages/sphinx/transforms/post_transforms/__init__.py", line 35, in apply
self.run(**kwargs)
File "/usr/lib/python3/dist-packages/sphinx/transforms/post_transforms/__init__.py", line 97, in run
self.warn_missing_reference(refdoc, typ, target, node, domain)
File "/usr/lib/python3/dist-packages/sphinx/transforms/post_transforms/__init__.py", line 204, in warn_missing_reference
logger.warning(msg, location=node, type='ref', subtype=typ)
File "/usr/lib/python3.11/logging/__init__.py", line 1855, in warning
self.log(WARNING, msg, *args, **kwargs)
File "/usr/lib/python3/dist-packages/sphinx/util/logging.py", line 123, in log
super().log(level, msg, *args, **kwargs)
File "/usr/lib/python3.11/logging/__init__.py", line 1887, in log
self.logger.log(level, msg, *args, **kwargs)
File "/usr/lib/python3.11/logging/__init__.py", line 1559, in log
self._log(level, msg, args, **kwargs)
File "/usr/lib/python3.11/logging/__init__.py", line 1634, in _log
self.handle(record)
File "/usr/lib/python3.11/logging/__init__.py", line 1644, in handle
self.callHandlers(record)
File "/usr/lib/python3.11/logging/__init__.py", line 1706, in callHandlers
hdlr.handle(record)
File "/usr/lib/python3.11/logging/__init__.py", line 974, in handle
rv = self.filter(record)
^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/logging/__init__.py", line 830, in filter
result = f.filter(record)
^^^^^^^^^^^^^^^^
File "/usr/lib/python3/dist-packages/sphinx/util/logging.py", line 426, in filter
raise exc
sphinx.errors.SphinxWarning: /home/alex/lsrc/qemu.git/qemu-options.hx:3884:'any' reference target not found: hub
Warning, treated as error:
/home/alex/lsrc/qemu.git/qemu-options.hx:3884:'any' reference target not found: hub
So it appears deep in sphinx itself and not any of our config bits... I
can't work out why its looking up hub as a reference though.
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
On Tue, Jan 21, 2025 at 4:23 PM Roman Penyaev <r.peniaev@gmail.com> wrote: > > On Tue, Jan 21, 2025 at 4:02 PM Alex Bennée <alex.bennee@linaro.org> wrote: > > > > Roman Penyaev <r.peniaev@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.peniaev@gmail.com> > > > Cc: "Marc-André Lureau" <marcandre.lureau@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 > > This is odd, my make is silent. Can you please check this? Docs generation was disabled on my side. My bad. The problem is in the `hub`, which should be ``hub``. Thanks for noticing that. -- Roman
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