diff options
Diffstat (limited to 'kernel/Documentation/braille-console.txt')
| -rw-r--r-- | kernel/Documentation/braille-console.txt | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/kernel/Documentation/braille-console.txt b/kernel/Documentation/braille-console.txt new file mode 100644 index 000000000..d0d042c2f --- /dev/null +++ b/kernel/Documentation/braille-console.txt @@ -0,0 +1,34 @@ + 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 <samuel.thibault@ens-lyon.org> |