Comment # 6 on bug 1195871 from Fabian Vogt

(In reply to Stefan Dirsch from comment #5)
> It's a SUSE specific patch in xkeyboard-config:
> n_suse-ctrl-alt-bksp-terminate.patch
> 
> /usr/share/X11/xkb/./rules/evdev
> [...]
>   $evdevkbds    =   +inet(evdev)+inet(%m)+terminate(ctrl_alt_bksp)
>   chromebook    =   +inet(evdev)+inet(chromebook)+terminate(ctrl_alt_bksp)
>   applealu_jis  =  
> +inet(evdev)+macintosh_vndr/jp(alujiskeys)+terminate(ctrl_alt_bksp)
>   *             =   +inet(evdev)+terminate(ctrl_alt_bksp)
> [...]

Yep, that's the cause of the issue.

What was this patch originally added for? If it's to enable ctrl_alt_bksp by
default, it's obsolete (and wrong in any case). All default keyboard
configurations already include it:
https://github.com/systemd/systemd/blob/9dfb429a44b0c7e4c50f35f888ac8ba3c677a994/src/locale/kbd-model-map

So can this just be dropped?

> Why is that an issue on Wayland? I don't get it. How do you kill an Xserver
> with that? Which one? Xwayland? How?

(Most) Wayland compositors use xkb keymaps (through libxkbcommon) and handle
XK_Terminate_Server like X.org.