What is Privileged mode?
A CPU operating mode reserved for the OS kernel, in which dangerous operations such as setting page tables and controlling I/O are allowed. It is distinguished from user mode, where applications run.
Field: OS & Hardware
Privileged mode in the explanations
CPUs therefore allow these operations only in privileged mode, reserving them for the OS kernel; attempting them in user mode raises an exception.
What is the main purpose of giving a CPU a privileged (kern…They use system calls: a dedicated instruction switches to privileged mode and invokes the kernel to read or write files, allocate memory, create processes and so on, then returns to user mode.
What is the mechanism by which applications ask the OS to p…When an exception or interrupt occurs, the CPU saves the return address along with the previous operating mode and interrupt-enable state in dedicated registers, then enters privileged mode.
When returning from an interrupt or exception handler, why …
Questions that mention Privileged mode (4)
- What is the main purpose of giving a CPU a privileged (kernel) mode and a user mode?
- What is the mechanism by which applications ask the OS to perform tasks such as file I/O?
- When returning from an interrupt or exception handler, why is a dedicated return instruction (such as RISC-V's sret or mret) used instead of an ordinary function return?
- When writing small data one byte at a time, why is accumulating it in a user-space buffer and writing in bulk faster than calling a system call each time?
Related terms
Context switch Demand paging Interrupt Return address System call TLB (translation lookaside buffer) ASID Copy-on-write Device driver Hypervisor