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108 lines
4.2 KiB
Plaintext
108 lines
4.2 KiB
Plaintext
= The udev keymap tool =
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== Introduction ==
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This udev extension configures computer model specific key mappings. This is
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particularly necessary for the non-standard extra keys found on many laptops,
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such as "brightness up", "next song", "www browser", or "suspend". Often these
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are accessed with the Fn key.
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Every key produces a "scan code", which is highly vendor/model specific for the
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nonstandard keys. This tool maintains mappings for these scan codes to standard
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"key codes", which denote the "meaning" of the key. The key codes are defined
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in /usr/include/linux/input.h.
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If some of your keys on your keyboard are not working at all, or produce the
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wrong effect, then a very likely cause of this is that the scan code -> key
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code mapping is incorrect on your computer.
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== Structure ==
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udev-keymap consists of the following parts:
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keymaps/*:: mappings of scan codes to key code names
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95-keymap.rules:: udev rules for mapping system vendor/product names and
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input module names to one of the keymaps above
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keymap:: manipulate an evdev input device:
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* write a key map file into a device (used by udev rules)
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* dump current scan → key code mapping
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* interactively display scan and key codes of pressed keys
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findkeyboards:: display evdev input devices which belong to actual keyboards,
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i. e. those suitable for the keymap program
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fdi2rules.py:: convert hal keymap FDIs into udev rules and key map files
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(Please note that this is far from perfect, since the mapping between fdi and
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udev rules is not straightforward, and impossible in some cases.)
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== Fixing broken keys ==
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In order to make a broken key work on your system and send it back to upstream
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for inclusion you need to do the following steps:
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1. Find the keyboard device.
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Run /lib/udev/findkeyboards. This should always give you an "AT
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keyboard" and possibly a "module". Some laptops (notably Thinkpads, Sonys, and
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Acers) have multimedia/function keys on a separate input device instead of the
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primary keyboard. The keyboard device should have a name like "input/event3".
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In the following commands, the name will be written as "input/eventX" (replace
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X with the appropriate number).
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2. Dump current mapping:
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sudo /lib/udev/keymap input/eventX > /tmp/orig-map.txt
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3. Find broken scan codes:
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sudo /lib/udev/keymap -i input/eventX
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Press all multimedia/function keys and check if the key name that gets printed
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out is plausible. If it is unknown or wrong, write down the scan code (looks
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like "0x1E") and the intended functionality of this key. Look in
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/usr/include/linux/input.h for an available KEY_XXXXX constant which most
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closely approximates this functionality and write it down as the new key code.
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For example, you might press a key labeled "web browser" which currently
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produces "unknown". Note down this:
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0x1E www # Fn+F2 web browser
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Repeat that for all other keys. Write the resulting list into a file. Look at
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/lib/udev/keymaps/ for existing key map files and make sure that you use the
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same structure.
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If the key only ever works once and then your keyboard (or the entire desktop)
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gets stuck for a long time, then it is likely that the BIOS fails to send a
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corresponding "key release" event after the key press event. Please note down
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this case as well, as it can be worked around in
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/lib/udev/keymaps/95-keyboard-force-release.rules .
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4. Find out your system vendor and product:
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cat /sys/class/dmi/id/sys_vendor
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cat /sys/class/dmi/id/product_name
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5. Generate a device dump with "udevadm info --export-db > /tmp/udev-db.txt".
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6. Send the system vendor/product names, the key mapping from step 3,
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/tmp/orig-map.txt from step 2, and /tmp/udev-db.txt from step 5
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to the bug tracker, so that they can be included in the next release:
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https://bugs.launchpad.net/udev/+bugs
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For local testing, copy your map file to /lib/udev/keymaps/ with an appropriate
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name, and add an appropriate udev rule to /lib/udev/rules.d/95-keymap.rules:
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* If you selected an "AT keyboard", add the rule to the section after
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'LABEL="keyboard_vendorcheck"'.
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* If you selected a "module", add the rule to the top section where the
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"ThinkPad Extra Buttons" are.
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== Author ==
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keymap is written and maintained by Martin Pitt <martin.pitt@ubuntu.com>.
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