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