Operating System in 1,000 Lines – Intro
94 comments
·January 8, 2025nuta
sesm
> Designing an OS is like creating your own world
Or like building your temple so you can talk to God directly
jb_briant
"Designing an OS is like creating your own world"
Making video game is also like creating your own world!
And it's order of magnitude less hard than making an OS...
Bonus point, you have a chance to make a living from it!
laurieg
Great resource, thanks for sharing.
I thought the written text was very high quality and didn't show many of the usual tells of a non-native writer. Could you share some details of how you used AI tools to help write it?
johndoe0815
Are you planning to also provide an English translation of your microkernel book? That sounds very interesting...
mayli
Nice project, short and concise enough for an undergrad to learn basic os concept and implementation.
viraj_shah
Hi OP, this looks super cool. I remember hearing about this (https://www.linuxfromscratch.org/) many years ago but have never done it.
Curious, what are the prerequisites for this? Do I have to know about how kernels work? How memory management, protection rings or processes are queued? Some I'd like to definitely learn about.
johnmaguire
LFS is about building a Linux distribution from scratch (i.e. using the Linux kernel.)
The book in question is about how to build your own operating system (i.e. a non-Linux) kernel from scratch.
> We'll implement basic context switching, paging, user mode, a command-line shell, a disk device driver, and file read/write operations in C. Sounds like a lot, however, it's only 1,000 lines of code!
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niutech
How does your book compare with the classic "Operating systems design and implementation" by Andrew S. Tanenbaum and Albert S. Woodhull implementing MINIX?
sydbarrett74
Did you post to OSDev?
exDM69
Very delightful article. Based on my experience in "hobby" OS programming, I would add setting up GDB debugging as early as possible. It was a great help in my projects and an improvement over debugging with the QEMU monitor only.
QEMU contains a built-in GDB server, you'll need a GDB client built for the target architecture (riscv in this case) and connecting to the QEMU GDB server over the network.
quruquru
Agree, and I'll add 3 other really useful QEMU features for osdev:
1) Record & Replay: Record an execution and replay it back. You can even attach GDB while replaying, and go back in time while debugging with "reverse-next" and "reverse-continue": https://qemu-project.gitlab.io/qemu/system/replay.html
2) The QEMU monitor, especially the "gva2gpa" and "xp" commands which are very useful to debug stuff with virtual memory
3) "-d mmu,cpu_reset,guest_errors,unimp": Basically causes QEMU to log when your code does something wrong. Also check "trace:help", there's a bunch of useful stuff to debug drivers
jannesan
thanks for sharing! qemu is very powerful, but it’s hard to discocer a lot of these features
o11c
> you'll need a GDB client built for the target architecture
Thankfully, GDB has a multiarch build these days which should work for all well-behaved targets in a single build.
(the place it is known to fail is for badly-behaved (embedded?) targets where there are configuration differences but no way to identify them)
ramon156
For any rust enthusiasts, phil-opp's guide is such a fun exercise to try out. It was actually the first thing I tried in Rust (very silly idea) and ended up only understanding ~5% of what I had just typed out.
I tried it again 2-3 years later and took the time to go over each subject. I even planned in advance to make sure I was going to finish it.
khaledh
Very cool to see someone tackling a small OS for RISC-V.
Shameless plug: I've written hobby OS (well, a kernel actually) in Nim for x86-64[0] and it's all documented as well. I put its development on hold until I create a JetBrains plugin for Nim (in heavy development right now).
elvis70
And discussed here a few months ago: https://news.ycombinator.com/item?id=40962767 - Fusion – A hobby OS implemented in Nim (110 comments)
agentkilo
Very cool! I just started to dvelve into RISC-V, and the book I'm reading (not in English) offers their own emulator[1], which, at a glance, is much simpler than QEMU, and comes with a weird license[2]. I wonder if people actually used it, since it looks like an academic project. Maybe I can also follow this tutorial and test it out.
[1] https://github.com/NJU-ProjectN/nemu/tree/master
[2] https://github.com/NJU-ProjectN/nemu/blob/master/LICENSE
Edit: wrong link
corank
It likely doesn't have performance that's good enough for production use. Doesn't look like there's JIT so it's all instruction by instruction interpreting.
markus_zhang
You can follow the MIT course and use QEMU if so wish.
sschmitt
Cool! Will be interesting to compare to https://github.com/mit-pdos/xv6-riscv!
Shameless plug for my html version of the xv6 book: https://xv6-guide.github.io/xv6-riscv-book/
pshirshov
xv6-riscv is 7000+ LoC. Half of that is userland utilities though.
davidw
> The tricky part of creating your own OS is debugging.
The older I get, the more I think I can figure out most problems that don't require some really gnarly domain expertise if I have a good way to iterate on them: code something, try it, see the results, see how they compare with what I wanted. It's when pieces of that are difficult or impossible, or very slow, things get more difficult.
unwind
Very nice, I always enjoy some low-level discussion like this.
I found a small typo/editing glitch on the "RISC-V 101 page" [1]:
- It's a trending CPU ("Instruction Set Architecture") recent years.
It should probably say "ISA" instead of "CPU", and the word "in" is missing from after the parentheses, right?
Edit: Markdown, don't format the quote as code. Oops.
1: https://operating-system-in-1000-lines.vercel.app/en/02-asse...
nuta
So do I :D
I was wondering that too. I'll update it with other examples (x86 and Arm).
pm2222
Two projects mentioned by this one:
https://github.com/nuta/microkernel-book/
https://github.com/mit-pdos/xv6-riscvvanderZwan
This looks nice! I would love to have an ebook version to read on my ereader. I wonder how much effort it would take to use the markdown files in the GH repo and convert those.
cheeseface
You can clone the repo and install pandoc. Then run "pandoc index.md *.md -o operating-system-in-1000-lines.epub" in "website/en/" folder and you will have a fully working ebook.
vanderZwan
Thank you for the tip!
atan2
Just a small typo in the RISC-V 101 chapter. It says "it's a trending CPU (ISA) recent years." I believe it should read "in recent years."
jraph
Don't hesitate to send the author an email, open a ticket or a PR to make sure they see this, it seems more appropriate than HN comments for this kind of things :-)
https://operating-system-in-1000-lines.vercel.app/en/17-outr...
wccrawford
I'm sure they know that those things were possible. Perhaps you could have done it instead?
They bothered to stop and suggest improvements here. That's enough work for them. They don't need to go elsewhere and do more, any more than you did.
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ChrisMarshallNY
I never counted, but my first professional software project was an operating system (firmware) for an RF switching box. It was written in 8085 ASM, and was probably in the neighborhood of 1,000 lines.
Apples to oranges, though. It was a specialized firmware system. Probably the biggest part was the IEEE-488 communications handler.
ChrisMarshallNY
This is it[0].
Looks like more like 2800 lines.
[0] https://littlegreenviper.com/wp-content/uploads/2022/07/TF30...
Author here.
I wrote this book so you can spend a boring weekend writing an operating system from scratch. You don’t have to write it in C - you can use your favorite programming language, like Rust or Zig.
I intentionally made it not UNIX-like and kept only the essential parts. Thinking about how the OS differs from Linux or Windows can also be fun. Designing an OS is like creating your own world—you can make it however you like!
BTW, you might notice some paragraphs feel machine-translated because, to some extent, they are. If you have some time to spare, please send me a PR. The content is written in plain Markdown [1].
Hope you enjoy :)
[1] https://github.com/nuta/operating-system-in-1000-lines/tree/...