Book Operating System Concepts 9th Edition Need solution to

Book: Operating System Concepts 9th Edition

Need solution to Exercise: 9.18
9.18 - A certain computer provides its users with a virtual memory space of 2^32 bytes. The computer has 2^22 bytes of physical memory. The virtual memory is implemented by paging, and the page size is 4,096 bytes. A user process generates the virtual address 11123456. Explain how the system establishes the corresponding physical location. Distinguish between software and hardware operations.

Solution

The virtual address in binary form is

Since the page size is 2**12, the page table size is 2**20. Therefore, the low-order 12 bits (0100 0101 0110) are used as the displacement into the page, while the remaining 20 bits (0001 0001 0001 0010 0011) are used as the displacement in the page table.

Consider the operations that are needed (a) for DAT, and (b) for page fault servicing. All the DAT operations are carried out in hardware. But of the list of operations for page faults, on pp. 297-298, *at*least* steps 2, 4, 5, 6, 8, 10, and 12 involve software operations.