Document the console=brl option and the usage of the braille screen
reader.
Signed-off-by: Samuel Thibault <[EMAIL PROTECTED]>
--- linux-2.6.24.1-orig/Documentation/kernel-parameters.txt 2008-01-25
09:31:45.000000000 +0100
+++ linux-2.6.24.1-perso/Documentation/kernel-parameters.txt 2008-02-23
13:21:27.000000000 +0100
@@ -463,6 +463,11 @@
switching to the matching ttyS device later. The
options are the same as for ttyS, above.
+ If the device connected to the port is not a TTY but a braille
+ device, prepend "brl," before the device type, for instance
+ console=brl,ttyS0
+ For now, only VisioBraille is supported.
+
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
--- linux-2.6.24.1-orig/Documentation/braille-console.txt 1970-01-01
01:00:00.000000000 +0100
+++ linux-2.6.24.1-perso/Documentation/braille-console.txt 2008-02-23
13:20:31.000000000 +0100
@@ -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 mecanism described in serial-console.txt
+
+For now, only the VisioBraille device is supported.
+
+Samuel Thibault <[EMAIL PROTECTED]>
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