xemu/docs/system/barrier.rst
Peter Maydell 4a64939db7 docs: Move user-facing barrier docs into system manual
The remaining text in docs/barrier.txt is user-facing description
of what the device is and how to use it. Move this into the
system manual and rstify it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20210727204112.12579-4-peter.maydell@linaro.org
2021-08-02 12:55:51 +01:00

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QEMU Barrier Client
===================
Generally, mouse and keyboard are grabbed through the QEMU video
interface emulation.
But when we want to use a video graphic adapter via a PCI passthrough
there is no way to provide the keyboard and mouse inputs to the VM
except by plugging a second set of mouse and keyboard to the host
or by installing a KVM software in the guest OS.
The QEMU Barrier client avoids this by implementing directly the Barrier
protocol into QEMU.
`Barrier <https://github.com/debauchee/barrier>`__
is a KVM (Keyboard-Video-Mouse) software forked from Symless's
synergy 1.9 codebase.
This protocol is enabled by adding an input-barrier object to QEMU.
Syntax::
input-barrier,id=<object-id>,name=<guest display name>
[,server=<barrier server address>][,port=<barrier server port>]
[,x-origin=<x-origin>][,y-origin=<y-origin>]
[,width=<width>][,height=<height>]
The object can be added on the QEMU command line, for instance with::
-object input-barrier,id=barrier0,name=VM-1
where VM-1 is the name the display configured in the Barrier server
on the host providing the mouse and the keyboard events.
by default ``<barrier server address>`` is ``localhost``,
``<port>`` is ``24800``, ``<x-origin>`` and ``<y-origin>`` are set to ``0``,
``<width>`` and ``<height>`` to ``1920`` and ``1080``.
If the Barrier server is stopped QEMU needs to be reconnected manually,
by removing and re-adding the input-barrier object, for instance
with the help of the HMP monitor::
(qemu) object_del barrier0
(qemu) object_add input-barrier,id=barrier0,name=VM-1