Linux Braille Console¶

To get early boot messages on a braille device (before userspace screenreaders can start), you first need to compile the support for the usual serialconsole (seeDocumentation/admin-guide/serial-console.rst), andfor braille device(inDevice Drivers ‣ Accessibility support ‣ Console on braille device).

Then you need to specify aconsole=brl, option on the kernel command line, theformat is:

console=brl,serial_options...

whereserial_options... are the same as described inDocumentation/admin-guide/serial-console.rst.

So for instance you can useconsole=brl,ttyS0 if the braille device is connected to the first serial port, andconsole=brl,ttyS0,115200 tooverride the baud rate to 115200, etc.

By default, the braille device will just show the last kernel message (consolemode). To review previous messages, press the Insert key to switch to the VTreview mode. In review mode, the arrow keys permit to browse in the VT content,PAGE-UP/PAGE-DOWN keys go at the top/bottom of the screen, andtheHOME key goes backto the cursor, hence providing very basic screen reviewing facility.

Sound feedback can be obtained by adding thebraille_console.sound=1 kernelparameter.

For simplicity, only one braille console can be enabled, other uses ofconsole=brl,... will be discarded. Also note that it does not interfere withthe console selection mechanism described inDocumentation/admin-guide/serial-console.rst.

For now, only the VisioBraille device is supported.

Samuel Thibault <samuel.thibault@ens-lyon.org>