GATE - 2005 | OS | Normally user programs are prevented from handling I/O directly by
Posted on 19-02-2022
GATE - 2005 [Operating System]
Question:
Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O?
|
A |
I/O protection is ensured by operating system routine(s) |
|
B |
I/O protection is ensured by a hardware trap |
|
C |
I/O protection is ensured during system configuration |
|
D |
I/O protection is not possible |
Solution:
Option (A) is Correct.
I/O protection can be ensured by operating system.
Because all the user application are not modified by user mode.
Those are sent to kernal mode as a system calls.
Thank You