Porting

Starina is designed to be highly portable. Arch-dependent code is clearly separated in the codebase, supports Device Tree, and leverages Cargo's build system to cross-compile OS.

Porting to a New Board

If Starina already supports the ISA (e.g. riscv64), it would be easy to port. You'll need to change:

• Kernel entry point. For example, riscv64_boot expects hart ID in a0, and device tree blob in a1 register on entry. Your board's bootloader may have a different protocol when entering the kernel.
• The base address in kernel.ld to match the board's memory map.
• Kernel memory areas mapped in kernel::arch::VmSpace::map_kernel_space.

TIP

Starina is still premature, and it does not have a fancy build config system like Linux's Kconfig. Try making it work first, hard-coded things everywhere, and then open a PR to discuss how we can generalize it.

Porting to a New ISA (CPU architecture)

You'll need to implement the following files:

• Install Rust toolchain
• kernel/src/arch/<arch>: Arch-dependent code in the kernel. kernel/src/arch/host is a good skeleton.
• run.sh: Change --target parameter for cargo build, and $QEMU for qemu.

TIP

To generate kernel.json template, you can use rustc's --print target-spec-json feature (documentation):

# Look for a suitable target to use
rustc --print target-list | grep x86_64

# Print a template target JSON for x86_64-unknown-none
rustc +nightly -Z unstable-options \
  --target=x86_64-unknown-none --print target-spec-json