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