blob: d0d042c2fd5e9e319657117b3de567b2d42a995a
1 | Linux Braille Console |
2 | |
3 | To get early boot messages on a braille device (before userspace screen |
4 | readers can start), you first need to compile the support for the usual serial |
5 | console (see serial-console.txt), and for braille device (in Device Drivers - |
6 | Accessibility). |
7 | |
8 | Then you need to specify a console=brl, option on the kernel command line, the |
9 | format is: |
10 | |
11 | console=brl,serial_options... |
12 | |
13 | where serial_options... are the same as described in serial-console.txt |
14 | |
15 | So for instance you can use console=brl,ttyS0 if the braille device is connected |
16 | to the first serial port, and console=brl,ttyS0,115200 to override the baud rate |
17 | to 115200, etc. |
18 | |
19 | By default, the braille device will just show the last kernel message (console |
20 | mode). To review previous messages, press the Insert key to switch to the VT |
21 | review mode. In review mode, the arrow keys permit to browse in the VT content, |
22 | page up/down keys go at the top/bottom of the screen, and the home key goes back |
23 | to the cursor, hence providing very basic screen reviewing facility. |
24 | |
25 | Sound feedback can be obtained by adding the braille_console.sound=1 kernel |
26 | parameter. |
27 | |
28 | For simplicity, only one braille console can be enabled, other uses of |
29 | console=brl,... will be discarded. Also note that it does not interfere with |
30 | the console selection mechanism described in serial-console.txt |
31 | |
32 | For now, only the VisioBraille device is supported. |
33 | |
34 | Samuel Thibault <samuel.thibault@ens-lyon.org> |
35 |