Documentation/braille-console.txt - kernel/common - Git at Google

                        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 serial-console.txt), and for braille device (in Device Drivers -
 Accessibility).

 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 serial-console.txt

 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,
 page up/down keys go at the top/bottom of the screen, and the 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 serial-console.txt

 For now, only the VisioBraille device is supported.

 Samuel Thibault <[email protected]>
	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 serial-console.txt), and for braille device (in Device Drivers -
	Accessibility).

	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 serial-console.txt

	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,
	page up/down keys go at the top/bottom of the screen, and the 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 serial-console.txt

	For now, only the VisioBraille device is supported.

	Samuel Thibault <[email protected]>