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

docs/barrier.txt

@@ -1,48 +0,0 @@
-                                QEMU Barrier Client
-
-
-* About
-
-    Barrier is a KVM (Keyboard-Video-Mouse) software forked from Symless's
-    synergy 1.9 codebase.
-
-    See https://github.com/debauchee/barrier
-
-* QEMU usage
-
-    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.
-
-    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 int 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 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
-

docs/system/barrier.rst

@@ -0,0 +1,44 @@
+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

docs/system/index.rst

@@ -20,6 +20,7 @@ or Hypervisor.Framework.
    linuxboot
    generic-loader
    guest-loader
+   barrier
    vnc-security
    tls
    secrets