Exception Levels §
- EL3
- Highest privilege level is typically used for so called
Secure Monitor
- EL3 firmware typically implements the Power State Coordination Interface (PSCI) for the lower ELs to use
- EL3 firmware typically involved into trusted boot
- EL2
- Targets the virtualization use-case
- EL at which hypervisors normally use for virtualization purposes.
- EL1
- Privileged parts of the OS kernels use
- EL0
- Most unprivileged level
- Runs most unprivileged codes (userspace application, userspace drivers, etc).
Reference §