1 Linux Braille Console 1 Linux Braille Console
2 ===================== 2 =====================
3 3
4 To get early boot messages on a braille device 4 To get early boot messages on a braille device (before userspace screen
5 readers can start), you first need to compile 5 readers can start), you first need to compile the support for the usual serial
6 console (see :ref:`Documentation/admin-guide/s 6 console (see :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), and
7 for braille device 7 for braille device
8 (in :menuselection:`Device Drivers --> Accessi 8 (in :menuselection:`Device Drivers --> Accessibility support --> Console on braille device`).
9 9
10 Then you need to specify a ``console=brl``, op 10 Then you need to specify a ``console=brl``, option on the kernel command line, the
11 format is:: 11 format is::
12 12
13 console=brl,serial_options... 13 console=brl,serial_options...
14 14
15 where ``serial_options...`` are the same as de 15 where ``serial_options...`` are the same as described in
16 :ref:`Documentation/admin-guide/serial-console 16 :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.
17 17
18 So for instance you can use ``console=brl,ttyS 18 So for instance you can use ``console=brl,ttyS0`` if the braille device is connected to the first serial port, and ``console=brl,ttyS0,115200`` to
19 override the baud rate to 115200, etc. 19 override the baud rate to 115200, etc.
20 20
21 By default, the braille device will just show 21 By default, the braille device will just show the last kernel message (console
22 mode). To review previous messages, press the 22 mode). To review previous messages, press the Insert key to switch to the VT
23 review mode. In review mode, the arrow keys p 23 review mode. In review mode, the arrow keys permit to browse in the VT content,
24 :kbd:`PAGE-UP`/:kbd:`PAGE-DOWN` keys go at the 24 :kbd:`PAGE-UP`/:kbd:`PAGE-DOWN` keys go at the top/bottom of the screen, and
25 the :kbd:`HOME` key goes back 25 the :kbd:`HOME` key goes back
26 to the cursor, hence providing very basic scre 26 to the cursor, hence providing very basic screen reviewing facility.
27 27
28 Sound feedback can be obtained by adding the ` 28 Sound feedback can be obtained by adding the ``braille_console.sound=1`` kernel
29 parameter. 29 parameter.
30 30
31 For simplicity, only one braille console can b 31 For simplicity, only one braille console can be enabled, other uses of
32 ``console=brl,...`` will be discarded. Also n 32 ``console=brl,...`` will be discarded. Also note that it does not interfere with
33 the console selection mechanism described in 33 the console selection mechanism described in
34 :ref:`Documentation/admin-guide/serial-console 34 :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.
35 35
36 For now, only the VisioBraille device is suppo 36 For now, only the VisioBraille device is supported.
37 37
38 Samuel Thibault <samuel.thibault@ens-lyon.org> 38 Samuel Thibault <samuel.thibault@ens-lyon.org>
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