Topic summary
Supervisor mode
Extracted from the Wikipedia article Protection ring.
Supervisor mode
In computer terms, supervisor mode is a hardware-mediated flag that can be changed by code running in system-level software. System-level tasks or threads may have this flag set while they are running, whereas user-level applications will not. This flag determines whether it would be possible to execute machine code operations such as modifying registers for various descriptor tables, or performing operations such as disabling interrupts. The idea of having two different modes to operate in comes from "with more power comes more responsibility" – a program in supervisor mode is trusted never to fail, since a failure may cause the whole computer system to crash.