Definition
Kernel Mode
Kernel Mode (or Privileged Mode) is a privileged execution state of the processor that grants the operating system unrestricted access to the instruction set architecture (ISA) and hardware resources.
Usage
The CPU enters Kernel Mode to execute trusted OS code (the kernel) for:
- Interrupt Handling: Responding to hardware signals.
- System Calls: Providing services requested by user processes.
- Exception Handling: Recovering from errors (traps).
In this mode, all machine instructions, including privileged ones (like I/O control or memory management), are allowed.