Question

In which one of the following modes, the hardware allows privileged instruction to be executed?

• A. Kernel mode
• B. Shell mode
• C. VM mode
• D. User mode

Hint:

Kernel Mode has complete access to CPU, memory and I/O devices, whereas User Mode has restricted access.

Answer 1

The Correct Option is A

Concept: Modern operating systems use dual-mode operation to protect system resources. The two execution modes are:
• User Mode
• Kernel Mode (Supervisor Mode) Privileged instructions are sensitive instructions that can directly access hardware resources and modify system settings.

Step 1: Understand privileged instructions.
Examples of privileged instructions include:
• I/O operations
• Memory management operations
• Interrupt control
• Process scheduling operations These instructions can affect the entire system.

Step 2: Determine where they can execute.
To prevent unauthorized access, the CPU allows these instructions only when running in Kernel Mode. User programs executing in User Mode cannot execute privileged instructions directly.

Step 3: Select the correct option.
Therefore, \[ \boxed{\text{Kernel Mode}} \] is the mode in which privileged instructions are executed.