xv6-riscv

MIT's xv6-riscv operating system, now in Rust!

This is a passion project for me - I've always wanted to write an operating system. I decided to port the xv6 operating system so that I could try porting a moderately sized codebase to my favorite programming language, Rust.

xv6 is a re-implementation of Dennis Ritchie's and Ken Thompson's Unix Version 6 (v6). xv6 loosely follows the structure and style of v6, but is implemented for a modern RISC-V multiprocessor using ANSI C.

To start the project, I made a basic Rust crate that compiled to a static library. At link time, the linker includes the static library into the final binary to result in a hybrid kernel. When the entire kernel is written in Rust, the link process should be a lot simpler (just Rust and assembly). At that point, I can start refactoring the kernel to use more of Rust's features that don't translate well across FFI boundaries.

Features

• Multi-core processing
• Paging
• Pre-emptive multitasking
• File system
• Process communication using pipes
• Entirely Rust kernel (no more C code)
• Round-robin scheduling
• Rust ABI for syscalls (I'll probably use stabby for this)
• Networking
• Running on real hardware (likely a Milk-V Duo)
• Port Rust standard library

Building and running

Build requirements:

• A RISC-V C toolchain
• QEMU (qemu-system-riscv64)
• A nightly Rust toolchain

The makefile is split into multiple levels to clearly separate scripts, but most important commands can be run from the project root.

• make kernel builds the kernel.
• make mkfs builds mkfs, the tool to help create the file system image.
• make fs.img uses mkfs to build the file system image.
• make qemu builds the kernel and file system, and then runs it in QEMU.
• make clean removes built artifacts, including from Rust.

Contributing

Pull requests will be ignored.

Authors and acknowledgements

Rewrite:

• Garen Tyler <garentyler@garen.dev>

Source:

xv6 is inspired by John Lions's Commentary on UNIX 6th Edition (Peer to Peer Communications; ISBN: 1-57398-013-7; 1st edition (June 14, 2000)). See also https://pdos.csail.mit.edu/6.1810/, which provides pointers to on-line resources for v6.

The following people have made contributions: Russ Cox (context switching, locking), Cliff Frey (MP), Xiao Yu (MP), Nickolai Zeldovich, and Austin Clements.

We are also grateful for the bug reports and patches contributed by Takahiro Aoyagi, Silas Boyd-Wickizer, Anton Burtsev, carlclone, Ian Chen, Dan Cross, Cody Cutler, Mike CAT, Tej Chajed, Asami Doi, eyalz800, Nelson Elhage, Saar Ettinger, Alice Ferrazzi, Nathaniel Filardo, flespark, Peter Froehlich, Yakir Goaron, Shivam Handa, Matt Harvey, Bryan Henry, jaichenhengjie, Jim Huang, Matúš Jókay, John Jolly, Alexander Kapshuk, Anders Kaseorg, kehao95, Wolfgang Keller, Jungwoo Kim, Jonathan Kimmitt, Eddie Kohler, Vadim Kolontsov, Austin Liew, l0stman, Pavan Maddamsetti, Imbar Marinescu, Yandong Mao, Matan Shabtay, Hitoshi Mitake, Carmi Merimovich, Mark Morrissey, mtasm, Joel Nider, Hayato Ohhashi, OptimisticSide, Harry Porter, Greg Price, Jude Rich, segfault, Ayan Shafqat, Eldar Sehayek, Yongming Shen, Fumiya Shigemitsu, Cam Tenny, tyfkda, Warren Toomey, Stephen Tu, Rafael Ubal, Amane Uehara, Pablo Ventura, Xi Wang, WaheedHafez, Keiichi Watanabe, Nicolas Wolovick, wxdao, Grant Wu, Jindong Zhang, Icenowy Zheng, ZhUyU1997, and Zou Chang Wei.

License

All code written by me in this project is LGPLv3 licensed. Any existing code appears to be under the MIT license.