Stellaream's Blog

Virtual memory provides a level of indirection -- the kernel can intercept memory references by marking PTEs invalid or read-only, leading to page faults, and can change what addresses mean by modifying PTEs. There is a saying in computer systems that any systems problem can be solved with a level of indirection. This lab explores an example -- copy-on-write fork.

This lab explores how system calls are implemented using traps. You will first do a warm-up exercises with stacks and then you will implement an example of user-level trap handling.

In this lab you will explore page tables and modify them to speed up certain system calls and to detect which pages have been accessed.

In the last lab you used system calls to write a few utilities. In this lab you will add some new system calls to xv6, which will help you understand how they work and will expose you to some of the internals of the xv6 kernel. You will add more system calls in later labs.

This lab will familiarize you with xv6 and its system calls.

Lab6 -- 信号量的实现和应用

Lab5 -- 进程运行轨迹的跟踪与统计

Lab4 -- 系统调用

Lab3 -- 操作系统的引导

Lab2 -- 调试分析 Linux 0.00 多任务切换