Question

Which of the following tasks is/are the responsibility/responsibilities of the memory management unit (MMU) in a system with paging-based memory management?

• A. Allocate a new page table for a newly created process
• B. Translate a virtual address to a physical address using the page table
• C. Raise a trap when a virtual address is not found in the page table
• D. Raise a trap when a process tries to write to a page marked with read-only permission in the page table

Hint:

The MMU handles address translation, permission checks, and traps for invalid memory accesses, while the operating system handles tasks like page table allocation.

Answer 1

The Correct Option is B

(A) Allocate a new page table for a newly created process: This task is typically handled by the operating system, not the MMU. Hence, Option (A) is incorrect.
(B) Translate a virtual address to a physical address using the page table: This is one of the core functions of the MMU. The MMU performs the translation of virtual addresses to physical addresses based on the page table. Hence, Option (B) is correct.
(C) Raise a trap when a virtual address is not found in the page table: The MMU raises a page fault trap when a virtual address is not found in the page table. This prompts the operating system to handle the fault. Hence, Option (C) is correct.
(D) Raise a trap when a process tries to write to a page marked with read-only permission in the page table: The MMU enforces memory protection by checking permissions in the page table. If a process violates these permissions, such as writing to a read-only page, the MMU raises a trap. Hence, Option (D) is correct. Final Answer: \[ \boxed{\text{(B), (C), (D)}} \]