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I use every single key on my laptop keyboard, with not one to spare. I recently got a Thinkpad T14 gen 5, which has a copilot key where PrtSc used to be. I was hoping to rebind the copilot key to be PrtSc (which I use heavily to resize windows), or at least map it to something (F23?) that I could intercept with my window manager for the same purposes.

Unfortunately, when I use showkey -s, pressing the copilot key gives 0xe0 0x5b 0x2a, and releasing 0xaa 0xe0 0xdb. I verified that 0xe0 0x5b / 0xe0 0xdb is just what I get for pressing / releasing the left windows key, and 0x2a / 0xaa is what I get for pressing / releasing the left shift key. So there doesn't seem to be a unique scan code for the copilot key.

If I use evtest, I get the following events from pressing/releasing copilot:

Event: time 1733647696.413560, type 4 (EV_MSC), code 4 (MSC_SCAN), value db Event: time 1733647696.413560, type 1 (EV_KEY), code 125 (KEY_LEFTMETA), value 1 Event: time 1733647696.413560, -------------- SYN_REPORT ------------ Event: time 1733647696.413794, type 4 (EV_MSC), code 4 (MSC_SCAN), value 2a Event: time 1733647696.413794, type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 1 Event: time 1733647696.413794, -------------- SYN_REPORT ------------ Event: time 1733647696.413922, type 4 (EV_MSC), code 4 (MSC_SCAN), value 6e Event: time 1733647696.413922, -------------- SYN_REPORT ------------ Event: time 1733647696.519973, type 4 (EV_MSC), code 4 (MSC_SCAN), value 6e Event: time 1733647696.519973, -------------- SYN_REPORT ------------ Event: time 1733647696.520192, type 4 (EV_MSC), code 4 (MSC_SCAN), value 2a Event: time 1733647696.520192, type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 0 Event: time 1733647696.520192, -------------- SYN_REPORT ------------ Event: time 1733647696.520475, type 4 (EV_MSC), code 4 (MSC_SCAN), value db Event: time 1733647696.520475, type 1 (EV_KEY), code 125 (KEY_LEFTMETA), value 0

So there is some kind of event unique to pressing copilot (namely MSC_SCAN 0x6e), but this doesn't seem to yield a corresponding keyscan event I can put into a keyboard map to load with loadkeys. If I could map that 0x6e event to F23, I could just have my window manager do the equivalent of the Print key on Win-Shift-F23, but I don't know how to do this.

My questions:

  • What is the relationship between the EV_MSC event values returned by evtest and the scan codes returned by showkey -s?
  • Is there some way to get the kernel to generate a key event from this EV_MSC 6e event? Can I do this with a keymap and loadkeys, or is there something lower-level I need to do?
  • Are there any other ways to be able to intercept the copilot key in my window manager to resize windows?
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It seems that the code 6e I get from evtest is a scancode that can be mapped to a keycode using the setkeycodes utility, and I don't understand what showkey -s is actually doing at all, but it's not outputting scan codes in the sense that setkeycodes/getkeycodes uses the term. Running:

setkeycodes 6e 99

makes it so that the copilot key maps to PrtSc, and it even allows SysRq commands. E.g., if you press Alt+(copilot, s) [i.e., press Alt, press copilot, release copilot, press s, release s, release Alt], the kernel will sync the disks.

When I went to check that SysRq functionality was working, it turns out journalctl -k actually had messages like "Unknown key pressed... Use 'setkeycodes 6e ' to make it known." So there you have it.

Here's a systemd unit file (/etc/systemd/system/copilot-key.service) that you can enable to do this automatically:

[Unit] Description=Map copilot key to Shift-Win-PrtSc After=local-fs.target [Service] Type=oneshot ExecStart=/usr/bin/setkeycodes 6e 99 ExecStop=/usr/bin/setkeycodes 6e 0 RemainAfterExit=yes [Install] WantedBy=multi-user.target
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