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- Linux Braille Console
- =====================
- To get early boot messages on a braille device (before userspace screen
- readers can start), you first need to compile the support for the usual serial
- console (see :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), and
- for braille device
- (in :menuselection:`Device Drivers --> Accessibility support --> Console on braille device`).
- Then you need to specify a ``console=brl``, option on the kernel command line, the
- format is::
- console=brl,serial_options...
- where ``serial_options...`` are the same as described in
- :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.
- 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
- override the baud rate to 115200, etc.
- By default, the braille device will just show the last kernel message (console
- mode). To review previous messages, press the Insert key to switch to the VT
- review mode. In review mode, the arrow keys permit to browse in the VT content,
- :kbd:`PAGE-UP`/:kbd:`PAGE-DOWN` keys go at the top/bottom of the screen, and
- the :kbd:`HOME` key goes back
- to the cursor, hence providing very basic screen reviewing facility.
- Sound feedback can be obtained by adding the ``braille_console.sound=1`` kernel
- parameter.
- For simplicity, only one braille console can be enabled, other uses of
- ``console=brl,...`` will be discarded. Also note that it does not interfere with
- the console selection mechanism described in
- :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.
- For now, only the VisioBraille device is supported.
- Samuel Thibault <samuel.thibault@ens-lyon.org>
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