lecture 14 Flashcards
Modes, Exceptions, and Processes
1
Q
kernel mode
A
CPU mode –> handles system instructions on behalf of the user
*handles system calls and commands that configure hardware
2
Q
user mode
A
CPU mode –> handles user instructions (code)
*cannot handle system calls/commands that configure hardware
3
Q
why are there 2 modes?
A
to handle different kinds of instructions
4
Q
when would kernel mode be used?
A
system calls, commands that configure hardware
5
Q
when would user mode be used?
A
user program instructions (code)
6
Q
types of synchronous exceptions
A
- trap (intentional system calls)
- fault (unintentional page faults)
- abort
7
Q
trap
A
returns to next instruction
8
Q
fault
A
page faults (recoverable)
protection faults (unrecoverable)
9
Q
abort
A
illegal instruction, machine check (unrecoverable)
10
Q
asynchronous exceptions
A
caused by an event external to the CPU
11
Q
types of asynchronous exceptions
A
- timer interrupter
- I/O interrupt from external device
