novos: A little kernel written in rust. (so I can learn osdev)

Running the kernel

To run the kernel, you need to have the following dependencies installed:

• qemu
• xorriso
• rustc and cargo
  • You need to have the x86_64-unknown-none target installed, and nightly rust.

    rustup override set nightly
    rustup target add x86_64-unknown-none
    # This isn't strictly necessary, but it's a good idea to update installed toolchains
    rustup update

Then, you can run the kernel with the following command from the root of the repository:

cargo run --bin bios_boot

Project structure

The project is split into several crates:

• kbuild: A library for building the kernel. Used in build.rs and the test runner.
• kernel: The main kernel crate.
• kproc: Various procedural macros used in the kernel. Currently only contains the test macro.
• kerial: A qemu serial driver for the kernel. Used for debugging.

Some other folders that appear in the root of the repository:

• boot_cfg: Configuration files for limine.
• boot_images: ISO images generated by the build process.
• output: Files generated by kserial commands.
• tools: Various python scripts used for debugging. Both scripts are currently old and unused.

Debugging the kernel

All debugging is done through environment variables. The following environment variables are supported:

Runtime options

• DEBUG: If set, QEMU will wait for a debugger to attach on port 1234.
• QEMU_FLAGS: Additional flags to pass to QEMU.
• VERBOSE: Shows QEMU's invocation command.
• NO_DISPLAY: Disables the graphical display in QEMU.
• KERNEL_MEM: Sets the amount of memory to allocate for the kernel in QEMU.
• ISO: Override the iso file to boot from.
• NO_EXIT: Prevents QEMU from exiting after the kernel exits.
• REBUILD: Forces a rebuild of the test binary. This will have no effect on the kernel itself, as the kernel is not build at runtime.

Build-time options

• ALLOC_DEBUG: If set, will print out information about memory allocations and deallocations.
• REINSTALL_LIMINE: If set, limine will be re-downloaded from it's git repository and reinstalled.
• ARTIFACT_DIR: The directory to store build artifacts in.
  • TODO: Rename this to BUILD_DIR or something.
• LIMINE_CONFIG: The path to the limine configuration file.
• ISO_NAME: The name of the ISO file to generate.
• ISO_ROOT: The directory to store ISO files in.