Extending xv6

I modified the xv6 operating system to demonstrate what I have learned in CS 451 (Operating Systems) about how an operating system functions. The xv6 operating system is a reimplementation of sixth edition Unix written in ANSI C. Although xv6 is simple when compared to modern operating systems, xv6 has all of the important features that a operating system needs to have. I started this project by understanding how system calls (calls to the operating system) worked through tracing through the source code. After figuring out how the system calls worked, I extended xv6 by adding new syscalls such as uv2p (user virtual address to physical address), and ps (get process state). Additionally, I added extent, a new file system, to the operating system. The extent file system works by storing consecutive references to blocks similar to an array.

This project helped me further improve my knowledge of low-level programming and how an operating system works. In addition to this course, I have also taken a course on microcomputer which covered how the hardware functions for system calls through the use of supervisor mode. After completing this project, I can write more efficient higher level programs using the experience that I have with operating systems.