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authorSamuel Thibault <samuel.thibault@ens-lyon.org>2008-04-30 00:54:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 08:29:52 -0700
commitf7511d5f66f01fc451747b24e79f3ada7a3af9af (patch)
tree934196c15e43077641e35286078a6753700a3e3d /Documentation
parent730f412c08c13858f7681bac0a2770fbc9159fed (diff)
downloadop-kernel-dev-f7511d5f66f01fc451747b24e79f3ada7a3af9af.zip
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Basic braille screen reader support
This adds a minimalistic braille screen reader support. This is meant to be used by blind people e.g. on boot failures or when / cannot be mounted etc and thus the userland screen readers can not work. [akpm@linux-foundation.org: fix exports] Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Cc: Jiri Kosina <jikos@jikos.cz> Cc: Dmitry Torokhov <dtor@mail.ru> Acked-by: Alan Cox <alan@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/braille-console.txt34
-rw-r--r--Documentation/kernel-parameters.txt5
2 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/braille-console.txt b/Documentation/braille-console.txt
new file mode 100644
index 0000000..000b0fb
--- /dev/null
+++ b/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 mecanism described in serial-console.txt
+
+For now, only the VisioBraille device is supported.
+
+Samuel Thibault <samuel.thibault@ens-lyon.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 3ce193f..0ba0861 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -496,6 +496,11 @@ and is between 256 and 4096 characters. It is defined in the file
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]
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