r9

r9

Plan 9 in Rust

R9 is a reimplementation of the plan9 kernel in Rust. It is not only inspired by but in many ways derived from the original Plan 9 source code.

Building

We use cargo and the xtask pattern to build the kernel.

To build r9 for x86_64, we assume you have cloned the git repository somewhere convenient. Then simply change into the top-level directory and, cargo xtask build --arch x86-64.

To build for aarch64, run cargo xtask build --arch aarch64 (Currently only Raspberry Pi 3 is supported).

There are other useful xtask subcommands; run cargo xtask help to see what is available.

Right now, r9 is not self-hosting.

Runtime Dependencies

cargo xtask dist, which cargo xtask qemu depends on, requires llvm-objcopy. This is expected to live in the rust toolchain path. You can install by running:

rustup component add llvm-tools

If you get No such file or directory (os error 2) messages, then install llvm separate from the rust toolchain and set:

OBJCOPY=$(which llvm-objcopy) cargo xtask qemukvm

If No such file or directory (os error 2) messages persist, check to ensure qemu or qemu-kvm is installed and the qemu-system-x86_64 binary is in your path (or qemu-system-aarch64 in the case of aarch64).

Running on Qemu

R9 can be run using qemu for the various supported architectures:

Arch	Platform	Commandline
aarch64	raspi3b	cargo xtask qemu --arch aarch64 --verbose
aarch64	raspi4b	cargo xtask qemu --arch aarch64 --config raspi4b --verbose
x86-64	q35	cargo xtask qemu --arch x86-64 --verbose
x86-64 (with kvm)	q35	cargo xtask qemu --arch x86-64 --kvm --verbose
riscv	virt	cargo xtask qemu --arch riscv64 --verbose

Running on Real Hardware™️

R9 has been run on the following hardware to a greater or lesser degree:

• Raspberry Pi 4 (Gets as far as printing 'r9' via the miniuart)

Raspberry Pi, Netboot

Assuming you can set up a TFTP server (good luck, it's incredibly fiddly, but for what it's worth, dnsmasq can work occasionally), and assuming the location of your netboot directory, you can build and copy the binary using the following command:

cargo xtask dist --arch aarch64 --verbose && cp target/aarch64-unknown-none-elf/debug/aarch64-qemu.gz ../netboot/kernel8.img

This copies a compressed binary, which should be much faster to copy across the network.

The Raspberry Pi firmware loads config.txt before the kernel. Here we can set which UART to use, amongst other things. The following contents will set up to use the miniuart:

enable_uart=1
core_freq_min=500