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1Linux Braille Console2=====================3 4To get early boot messages on a braille device (before userspace screen5readers can start), you first need to compile the support for the usual serial6console (see :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), and7for braille device8(in :menuselection:`Device Drivers --> Accessibility support --> Console on braille device`).9 10Then you need to specify a ``console=brl``, option on the kernel command line, the11format is::12 13 console=brl,serial_options...14 15where ``serial_options...`` are the same as described in16:ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.17 18So for instance you can use ``console=brl,ttyS0`` if the braille device is connected to the first serial port, and ``console=brl,ttyS0,115200`` to19override the baud rate to 115200, etc.20 21By default, the braille device will just show the last kernel message (console22mode). To review previous messages, press the Insert key to switch to the VT23review 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 top/bottom of the screen, and25the :kbd:`HOME` key goes back26to the cursor, hence providing very basic screen reviewing facility.27 28Sound feedback can be obtained by adding the ``braille_console.sound=1`` kernel29parameter.30 31For simplicity, only one braille console can be enabled, other uses of32``console=brl,...`` will be discarded. Also note that it does not interfere with33the console selection mechanism described in34:ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.35 36For now, only the VisioBraille device is supported.37 38Samuel Thibault <samuel.thibault@ens-lyon.org>39