mirror of https://gitee.com/openkylin/linux.git
35 lines
1.4 KiB
Plaintext
35 lines
1.4 KiB
Plaintext
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Linux Braille Console
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To get early boot messages on a braille device (before userspace screen
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readers can start), you first need to compile the support for the usual serial
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console (see serial-console.txt), and for braille device (in Device Drivers -
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Accessibility).
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Then you need to specify a console=brl, option on the kernel command line, the
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format is:
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console=brl,serial_options...
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where serial_options... are the same as described in serial-console.txt
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So for instance you can use console=brl,ttyS0 if the braille device is connected
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to the first serial port, and console=brl,ttyS0,115200 to override the baud rate
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to 115200, etc.
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By default, the braille device will just show the last kernel message (console
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mode). To review previous messages, press the Insert key to switch to the VT
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review mode. In review mode, the arrow keys permit to browse in the VT content,
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page up/down keys go at the top/bottom of the screen, and the home key goes back
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to the cursor, hence providing very basic screen reviewing facility.
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Sound feedback can be obtained by adding the braille_console.sound=1 kernel
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parameter.
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For simplicity, only one braille console can be enabled, other uses of
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console=brl,... will be discarded. Also note that it does not interfere with
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the console selection mecanism described in serial-console.txt
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For now, only the VisioBraille device is supported.
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Samuel Thibault <samuel.thibault@ens-lyon.org>
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