rust-osdev-jumpstart

Rust, cargo and QEMU setup for multi-architecture OS development.

Goal

This repo should give you a boost in starting a bare-metal OS development project in Rust. You can go backwards from here if you just want something working as a starting point (but have different ideas for foundation), or you can go forward and exploit the testing setup.

Sources

These three are the great Rust bare-metal OS development blogs, and I have borrowed liberally from their ideas and code.

• Philipp Oppermann - x86_64
• Andre Richter - Arm
• Stephen Marz - RiscV

Features

• Doc tests and unit tests run your development host OS for speed.
• Integration tests are run under QEMU with cargo test --target <triple>.
• Integration tests utilise custom test frameworks feature for convenient test suites.
• QEMU passes back test result to cargo using qemu_exit.
• make test_all runs doc, unit and integration tests for all three architectures.
• QEMU definitions largely follow the platform-specific blogs above.

Example usage

$ make test_all
cargo test --doc --target=x86_64-apple-darwin
    Finished test [unoptimized + debuginfo] target(s) in 0.01s
   Doc-tests libkernel

running 1 test
test src/lib.rs - (line 4) ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.47s

cargo test --lib --target=x86_64-apple-darwin
    Finished test [unoptimized + debuginfo] target(s) in 0.01s
     Running target/x86_64-apple-darwin/debug/deps/libkernel-910fb71f27dff6a6

running 1 test
test test::panics_ok ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

cargo test --target x86_64-unknown-none.json -Zunstable-options -Zbuild-std=core,compiler_builtins -Zbuild-std-features=compiler-builtins-mem
    Finished test [unoptimized + debuginfo] target(s) in 0.04s
     Running target/x86_64-unknown-none/debug/deps/000_kernel_init-f9ceeb28812f2f47
Building bootloader
   Compiling bootloader v0.9.11 (~/.cargo/registry/src/github.com-1ecc6299db9ec823/bootloader-0.9.11)
    Finished release [optimized + debuginfo] target(s) in 1.14s
Running: `qemu-system-x86_64 -drive format=raw,file=target/x86_64-unknown-none/debug/deps/bootimage-000_kernel_init-f9ceeb28812f2f47.bin -no-reboot -device isa
     Running target/x86_64-unknown-none/debug/deps/001_should_panic-6a56cc56ef6b6077
Building bootloader
   Compiling bootloader v0.9.11 (~/.cargo/registry/src/github.com-1ecc6299db9ec823/bootloader-0.9.11)
    Finished release [optimized + debuginfo] target(s) in 1.11s
Running: `qemu-system-x86_64 -drive format=raw,file=target/x86_64-unknown-none/debug/deps/bootimage-001_should_panic-6a56cc56ef6b6077.bin -no-reboot -device is
cargo test --target riscv64gc-unknown-none-elf
    Finished test [unoptimized + debuginfo] target(s) in 0.01s
     Running target/riscv64gc-unknown-none-elf/debug/deps/000_kernel_init-af9782dbeaca1763
     Running target/riscv64gc-unknown-none-elf/debug/deps/001_should_panic-db251fb771fa34a8
cargo test --target aarch64-unknown-none-softfloat
    Finished test [unoptimized + debuginfo] target(s) in 0.01s
     Running target/aarch64-unknown-none-softfloat/debug/deps/000_kernel_init-13b9d95425b9c0bb
     Running target/aarch64-unknown-none-softfloat/debug/deps/001_should_panic-e72d04dcc4d61eda

Known limitations and extensions

Pull requests welcome!

• Only tested on Mac OS 11 Big Sur.
• Running the doc and unit tests on the host means those tests can't interact with hardware. Even to unit test the architecture-independent code would require either a mock _arch/test or lots of cfg(test) peppered through-out.
• Utilising -Zmultitarget would be an improvement, but the -Zbuild-std options required for x86_64 can't be pushed into [target.x86_64...] inside .cargo/config.toml. You would probably still need make as a shorthand.
• Logging would be a great inclusion, but might be quite opinionated with quite a bit of serial device code.
• Device tree management in the Makefile for RiscV and Arm.

Other influences

• Julia Evans
• Bodil Stokke
• Lucas Hartmann We follow in his footsteps!
• Dawid Ciężarkiewicz And Dawid's too!
• rCoreOS Multi-arch
• Ilya Kartashov
• Redox OS