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1 | Linux Braille Console |
2 | ===================== | |
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3 | |
4 | To get early boot messages on a braille device (before userspace screen | |
5 | readers can start), you first need to compile the support for the usual serial | |
8c27ceff | 6 | console (see :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), and |
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7 | for braille device |
8 | (in :menuselection:`Device Drivers --> Accessibility support --> Console on braille device`). | |
f7511d5f | 9 | |
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10 | Then you need to specify a ``console=brl``, option on the kernel command line, the |
11 | format is:: | |
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12 | |
13 | console=brl,serial_options... | |
14 | ||
8e7fbec6 | 15 | where ``serial_options...`` are the same as described in |
8c27ceff | 16 | :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`. |
f7511d5f | 17 | |
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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. | |
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20 | |
21 | By default, the braille device will just show the last kernel message (console | |
22 | mode). To review previous messages, press the Insert key to switch to the VT | |
23 | review mode. In review mode, the arrow keys permit to browse in the VT content, | |
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24 | :kbd:`PAGE-UP`/:kbd:`PAGE-DOWN` keys go at the top/bottom of the screen, and |
25 | the :kbd:`HOME` key goes back | |
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26 | to the cursor, hence providing very basic screen reviewing facility. |
27 | ||
8e7fbec6 | 28 | Sound feedback can be obtained by adding the ``braille_console.sound=1`` kernel |
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29 | parameter. |
30 | ||
31 | For simplicity, only one braille console can be enabled, other uses of | |
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32 | ``console=brl,...`` will be discarded. Also note that it does not interfere with |
33 | the console selection mechanism described in | |
8c27ceff | 34 | :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`. |
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35 | |
36 | For now, only the VisioBraille device is supported. | |
37 | ||
38 | Samuel Thibault <samuel.thibault@ens-lyon.org> |