Programming Assignment 4
CS 30200/ECE 46810
Operating Systems
Spring, 2019

This assignment makes use of files contained in this zip file. This assignment is due Friday, April 26.

For this assignment you are to write a program that performs virtual memory operations. You will run the program along with a virtual memory mapping program so that you can observe the virtual memory operations.

Complete the program that is outlined in the file VMdriver.c from the above zip file. Create a text file, called VMcmds.txt, with commands to exercise your virtual memory operations. The form of the command file is described in the comments of VMdriver.c. A simple version of VMcmds.txt is contained in hw4.zip. Your command file should demonstrate all of the commands described in the comments of VMdriver.c. Be sure to create a command file that really tests your program. Run your program in a console window using a command of the form

   C:\VMdriver.exe < VMcmds.txt

Your VMdriver.exe program should create a process from the program VMmapper.exe (its source code file, VMmapper.c, is included in the zip file). The VMmapper.exe process will display a memory map of the VMdriver.exe process as it is running so that you can see the virtual memory operations take place in the VMdriver.exe virtual address space.

In the zip file there is a demo version, VMdriver-demo.exe, that you can run to see how your version should work.

When you are done with your version of VMdriver.c, here are some questions that you should think about. To answer these questions, you will need to use your version of VMdriver.exe, the VMmapper.exe program, and you may need to use other programs that let you observe virtual memory.

• 1) After you have committed a block of pages, how can you observe the effect of the "Touch pages in a block" command? (Hint: You will need to use another program.)
• 2) How can you observe the effect of the "Lock a block of pages" command? (Hint: Use one or two of the programs that we demonstrated in class.)
• 3) What happens when you touch a reserved but noncommitted page of virtual memory?
• 4) What happens when you touch a guard page?
• 5) What happens when you write to a page with access code PAGE_READONLY? How can you test this?
• 6) What happens when you touch and/or write to a page with access code PAGE_EXECUTE? (What about PAGE_EXECUTE_READ?)

Turn in a zip file called CS302Hw4Surname.zip (where Surname is your last name) containing your version of VMdriver.c and your command file VMcmds.txt.

This assignment is due Friday, April 26.

Here are links to some Windows API documentation that you might need to use in this assignment.

• GetCurrentProcessId
• VirtualAlloc
• VirtualFree
• VirtualLock
• VirtualUnLock
• Virtual Memory Functions
• Page State
• Memory Protection Constants
• Data Execution Prevention
• Working with Pages
• Process Working Set
• Memory Management
• Memory Management Reference