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This is a lightweight and secure multiprocessor microkernel operating system written in Rust for 32-bit and 64-bit RISC-V systems.

It is a work in progress: I'm starting from scratch after previously writing a working microkernel for 32-bit SMP x86 computers in C and assembly.

I learned a lot from that foray, and so this is the second iteration of diosix. Crucially, it will be written in Rust, a C/C++-like programming language that has a fierce emphasis on guaranteed memory safety, threads without data races, and other security features. I chose RISC-V because it's interesting new ground to explore, whereas there are countless x86 and Arm operating system kernels out there.

Running and building

See the build instructions for step-by-step guides to compiling and running this project. Here's a screenshot of the kernel booting in a 32-bit octo-core Qemu Virt hardware environment, and writing some debug out to the virtual serial port:

Screenshot of SMP diosix in Qemu

The commands to build and run this code:

./ --triple riscv32imac-unknown-none-elf --platform qemu32_virt
qemu-system-riscv32 -machine virt -kernel target/riscv32imac-unknown-none-elf/release/kernel -nographic -smp 8

Press Ctrl-a then c to escape to the Qemu monitor, then q to quit.


There are a number of goals to hit before this can be considered a useful kernel and operating system. Here's a non-complete todo list:

  • Update wiki with relevant documentation
  • Bring-up for RV32
  • Bring-up for RV64
  • Kernel level:
    • Physical RAM region management
    • Exception handling
    • Interrupt handling
    • CPU core scheduling
    • Supervisor environment management
  • Supervisor level:
    • Physical RAM page management
    • Virtual page management
    • Exception handling
    • Interrupt handling
    • CPU core scheduling
    • ELF executable parsing and loading
    • User environment management


All current development work is done in master and targets RISC-V. The x86 branch holds an early port of the Rust microkernel for Intel-compatible PC systems. The x86hypervisor branch holds an early attempt to build hypervisor features into the x86 branch. You're welcome to update these so they catch up with master, however my focus will be on the RISC-V port.


Feel free to email me, Chris Williams, if you have any questions, want to get involved, have source to contribute, or found a security flaw. You can also find me, diodesign, on Freenode IRC in the #osdev channel, or on Twitter. Ultimately, you can submit pull requests or issues on GitHub.

Copyright, license, and thanks

Copyright © Chris Williams and contributors, 2018. See LICENSE for source code and binary distribution and use.

src/contrib/hermit-dtb: Copyright © 2018 Colin Finck, RWTH Aachen University.

With thanks to David Craven and everyone else who helped port Rust to RISC-V, the RISC-V world for designing the CPUs and writing the emulators in the first place, Philipp Oppermann for his guide to writing kernel-level Rust code, and to the OSdev community for its notes and documentation.