Definition
Kernel Mode
Kernel Mode (privileged/supervisor mode) is a highly privileged execution state granting the OS unrestricted access to all machine instructions and hardware resources.
The kernel resides in this state to manage resources and abstract hardware. In this mode, the OS can modify control structures, manage memory via page tables, and communicate directly with I/O controllers.
Usage
Interrupt Handling
Responding to asynchronous hardware signals.
System Calls
Providing protected services requested by user processes. See User vs. Kernel Mode.
Exception Handling
Recovering from software errors (traps).