My question is simple. xev isn't registering Fn+F4 keypress on my Asus FX505DT running Kubuntu 19.10. So, how shall I proceed with solving this issue?

  • Some FN keys on laptops are handled directly by some firmware and do not even reach the OS. Check by switching to a virtual terminal with Ctrl-Alt-Fx and running the showkeys program
    – pizdelect
    Mar 28, 2020 at 11:33
  • Thanks for the response, using showkey I finally got some response: 248. Mar 28, 2020 at 11:59
  • Additionally, I found out that showkey and xev both don't register Fn+F5. How should I go about fixing that? Mar 28, 2020 at 11:59
  • Update: Using evtest, I've found that keysym 248 comes under a separate device named as Asus WMI hotkeys. How can I use this input with i3wm? Mar 29, 2020 at 6:45

1 Answer 1


After this much much time, I've figured out how to make this Fn + F4 keypress recognizable by xev. The issue started with this key combination having the keycode 248 which isn't interpreted by the X Window system since it only accepts keycodes between 8 - 255.

Apparently, 248 is the keycode interpreted by showkey in the virtual console and 8 has to be added to it, which makes it greater than 255. (I don't have any reference for this but I've read this on many threads.)

Once I found out the issue, the solution was simple, to re-allocate the Fn+F4 keypress somewhere between 8 - 255. I found the unassigned keycodes using xmodmap -pke, and in my case I went with 120. Afterwards, I proceeded using this tutorial.

In my case, showkey -s wan't returning anything so I had to use getkeycodes.

Once the keycode 120 was assigned to Fn + F4, I assigned the XF86AudioMicMute symbol to it using xmodmap.

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