[SOLVED] Remapping keys using udev hwdb doesn't work on rightAlt

Question

hi, I had posted this topic in the [ newbie corner ] subforum for days, but got no repliy. I hope I can find luck  here.
I'm trying to use udev hwdb for swapping pairs of keys ( esc, caps_lock ) and ( rightAlt , rightCtrl ) . I followed the instruction here Map Scancodes to Keycodes   with procedures describe blow. I only succeed in exchanging pair (esc, caps_lock) but failed in (rightAlt, rightCtrl).
Details of Procedures:
Create an empty file under /usr/lib64/udev/hwdb.d with file name 90-custom-keys.hwdb . Add the following lines into this file.
keyboard:dmi:bvn*:bvr*:bd*:svnDell*:pn*
KEYBOARD_KEY_01=capslock
KEYBOARD_KEY_3a=esc
KEYBOARD_KEY_e038=rightctrl
KEYBOARD_KEY_e01d=rightalt
Rebuilding hwdb.bin
udevadm hwdb --update
Testing and reboot my system
udevadm --debug test /devices/platform/i8042/serio0/input/input0/event0
udevadm --debug test-builtin keyboard /devices/platform/i8042/serio0/input/input0/event0
Parts of the testing result of the last command looks like
device 0x1ce3890 has devpath '/devices/platform/i8042/serio0/input/input0/event0'
device 0x1ce3890 filled with db file data
keyboard: mapping scan code 1 (0x1) to key code 58 (0x3a)
keyboard: mapping scan code 58 (0x3a) to key code 1 (0x1)
keyboard: mapping scan code 129 (0x81) to key code 164 (0xa4)
keyboard: mapping scan code 130 (0x82) to key code 166 (0xa6)
keyboard: mapping scan code 164 (0xa4) to key code 166 (0xa6)
keyboard: mapping scan code 216 (0xd8) to key code 152 (0x98)
keyboard: mapping scan code 217 (0xd9) to key code 191 (0xbf)
keyboard: mapping scan code 57373 (0xe01d) to key code 100 (0x64)
Error calling EVIOCSKEYCODE: Invalid argument
keyboard: mapping scan code 57400 (0xe038) to key code 97 (0x61)
Error calling EVIOCSKEYCODE: Invalid argument
keyboard: mapping scan code 237 (0xed) to key code 226 (0xe2)
unload module index
Thie last 6 lines seems to be complaining the  problem, saying that 0xe038  and 0xe01d are invalid scancodes.
But they are scancodes of rightAlt and rightCtrl respectively, which I got from
showkey -s
After rebooting the system with the above settings, esc works as caps_lock and caps_lock works as  esc but  rightAlt and rightCtrl has no changes.
Last edited by kejingzhang (2013-10-10 02:32:29)

Answer 1

Thanks plam and Raynman for your help . Follow your hints, I succeed the swapping key task in an alternative method.
Using the command 'setkeycodes' and adding these commands into a systemd controlled service script, keymaps are exchanged as gdm started.
Here is my script and steps for doing this.
Created a file with filename custom-keys.service under /etc/systemd/system. Add the  following context to the file.
[Unit]
Description=Keymap Custom
Requires=gdm.service
After=gdm.service
[Service]
Type=oneshot
ExecStart=/usr/bin/setkeycodes 1 58
ExecStart=/usr/bin/setkeycodes 3a 1
ExecStart=/usr/bin/setkeycodes e01d 100
ExecStart=/usr/bin/setkeycodes e038 97
[Install]
WantedBy=graphical.target
Enable the script so setkeycodes commands will automatically executed when gdm starts
systemctl enable custom-keys
The next time you reboot your system, key changes will take effect. To test if your config works, try
systemctl start custom-keys