[systemd-devel] logind on VT-less kernels, and starting a greeter on session hangs

[nerdopolis]

While on VT-less seats, while all major Wayland compositors support CTRL+ALT+F(x), the drawback is that on VT-less seats and kernels, it only works when there are multiple sessions on VT-less seats to switch between, as most display managers stop the greeter when starting a session, and a large majority of the time, only one user is logged in at once.

I am thinking mostly of if the session hangs, or when kscreenlocker crashes on KDE, and it instructs the user on how to login to start another session.

(Also, this can happen now, but in instances where the compositor becomes totally unresponsive, the compositor or session no longer is able to handle the Ctrl+Alt+F(x) keys, and running commands then requires a remote SSH connection)

I am thinking a rescue key sequence that logind itself could listen for (since it already seems to be handling some other keys like Sleep and Hibernate keys), and then in turn maybe emit a Dbus signal that login managers will respond to, and switch to or re-launch the greeter on the seat that the key sequence was pressed on.

There is also the question on what key command it should be, In my mind pressing and *long holding* Ctrl+Alt+Esc seems the most logical, but then that would mean logind would get woken up every time Ctrl and Alt is hit, and that could have a slight impact on battery usage.
I was also thinking pressing and holding Caps+Esc? It has to be keys on most keyboards, and it seems *some* laptops manufacturers made it their mission to not give many options.

What do you think? Or is this outside of the scope of logind, and should the display manager do that instead?

Thanks