There is a mysterious tty that only reacts to sysrq, not to any other keyboard input.
It started after I engaged SysRQ+F and SysRq+i.
Every 30 seconds or so, Linux switches away from the current tty to that strange, uncontrollable tty that contains the most recent dmesg's.
Each line starts with the uptime such as [2312154.4828572]
Ctrl+Alt+F# does not get me out of there.
What is this mysterious tty?