SETKEYCODES

Section: Keyboard Support (8)
Updated: 8 Nov 1994
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NAME

setkeycodes - load kernel scancode-to-keycode mapping table entries

SYNOPSIS

setkeycodes scancode keycode ...

DESCRIPTION

The setkeycodes command reads its arguments two at a time, each pair of arguments consisting of a scancode (given in hexadecimal) and a keycode (given in decimal). For each such pair, it tells the kernel keyboard driver to map the specified scancode to the specified keycode.

This command is useful only for people with slightly unusual keyboards, that have a few keys which produce scancodes that the kernel does not recognize.

THEORY

The usual PC keyboard produces a series of scancodes for each key press and key release. (Scancodes are shown by showkey -s, see showkey(1).) The kernel parses this stream of scancodes, and converts it to a stream of keycodes (key press/release events). (Keycodes are shown by showkey.) Apart from a few scancodes with special meaning, and apart from the sequence produced by the Pause key, and apart from shiftstate related scancodes, and apart from the key up/down bit, the stream of scancodes consists of unescaped scancodes xx (7 bits) and escaped scancodes e0 xx (8+7 bits). It is hardwired in the current kernel that in the range 1-88 (0x01-0x58) keycode equals scancode. For the remaining scancodes (0x59-0x7f) or scancode pairs (0xe0 0x00 - 0xe0 0x7f) a corresponding keycode can be assigned (in the range 1-127). For example, if you have a Macro key that produces e0 6f according to showkey(1), the command

: setkeycodes e06f 112

will assign the keycode 112 to it, and then loadkeys(1) can be used to define the function of this key.

USB keyboards have standardized keycodes and setkeycodes doesn't affect them at all.

2.6 KERNELS

In 2.6 kernels key codes lie in the range 1-255, instead of 1-127. (It might be best to confine oneself to the range 1-239.)

In 2.6 kernels raw mode, or scancode mode, is not very raw at all. The code returned by showkey -s will change after use of setkeycodes. A kernel bug. See also showkey(1).

OPTIONS

None.

BUGS

The keycodes of X have nothing to do with those of Linux. Unusual keys can be made visible under Linux, but not under X.

setkeycodes affects only the "first" input device that has modifiable scancode-to-keycode mapping. If there is more than one such device, setkeycodes cannot change the mapping of other devices than the "first" one.

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Time: 05:34:30 GMT, December 24, 2015