MIT 6.S081: Operating System Engineering
Descriptions
- Offered by: MIT
- Prerequisites: Computer architecture basics, C programming
- Programming Language: C
- Difficulty: 🌟🌟🌟🌟
- Class Hour: 80+
MIT 6.S081 (formerly 6.828) is MIT's operating system course, built around the xv6 teaching OS. It's widely regarded as one of the best OS courses in the world — not because it covers the most material, but because it has you actually implement an operating system.
The course centers on 7 labs, each requiring you to add a core feature to the xv6 kernel: process management, memory management, file systems, networking, and more. After completing these labs, your understanding of operating systems will surpass 90% of CS graduates.
Course Resources
- Website: pdos.csail.mit.edu/6.828
- Lectures: YouTube 2020
- Textbook: xv6 Book (free PDF)
- Lab code: xv6-riscv
Lab List
| Lab | Content | Difficulty |
|---|---|---|
| Lab 1: Unix utilities | Implement xarg, sleep, etc. | 🌟 |
| Lab 2: System calls | Add system calls, understand kernel mode | 🌟🌟 |
| Lab 3: Page tables | Implement page tables, understand virtual memory | 🌟🌟🌟 |
| Lab 4: Traps | Implement interrupt and exception handling | 🌟🌟🌟 |
| Lab 5: Copy-on-write fork | Implement copy-on-write | 🌟🌟🌟 |
| Lab 6: Multithreading | Implement threading and locks | 🌟🌟🌟🌟 |
| Lab 7: Network driver | Implement network driver | 🌟🌟🌟🌟 |
| Lab 8: File system | Implement file system | 🌟🌟🌟🌟🌟 |
| Lab 9: mmap | Implement memory mapping | 🌟🌟🌟🌟 |
Self-Study Tips
Read the first 3 chapters of the xv6 Book first. Don't jump straight into labs. Understand xv6's basic architecture (process, memory, file system implementation) before writing code.
Allocate 1-2 weeks per lab. Labs increase in difficulty; later ones (file system, mmap) may take 2+ weeks. Don't rush.
Master GDB debugging. Debugging OS code is different from normal programs. Learning to debug kernel code with GDB is one of the most important skills from this course.
Reference, don't copy. Many reference implementations are available online, but copying them means you learn nothing. Think first, then look at references when stuck.
Notes
This course has a massive workload, but the rewards are equally huge. If you can complete all labs independently, any OS interview question will be within your reach.
The 2023+ version switched from x86 to RISC-V architecture with cleaner lab code. The new version is recommended.