Module boot 

Bootloader-to-kernel handoff ABI.

This module defines the data structures passed from the bootloader (Limine) to the kernel at entry point. The kernel reads these structures to discover memory layout, ACPI tables, framebuffer configuration, and kernel modules.

Boot flow

BIOS/UEFI → Limine bootloader → kernel_main(KernelArgs)

The bootloader populates KernelArgs on the initial stack or in a reserved memory region, then jumps to the kernel entry point with a pointer to this structure in a register (typically RDI on x86_64).

ABI stability

The KernelArgs layout is frozen per ABI version. Changing the layout requires bumping STRAT9_BOOT_ABI_VERSION and updating both bootloader and kernel simultaneously.

Example (kernel side)

// In kernel_main():
unsafe fn kernel_main(args: *const KernelArgs) -> ! {
    let args = &*args;

    // Validate magic number
    assert_eq!(args.magic, STRAT9_BOOT_MAGIC);

    // Validate ABI version
    assert_eq!(args.abi_version, STRAT9_BOOT_ABI_VERSION);

    // Use memory map to initialize buddy allocator
    let mmap = core::slice::from_raw_parts(
        args.memory_map_base as *const MemoryRegion,
        args.memory_map_size as usize / core::mem::size_of::<MemoryRegion>(),
    );

    // Use ACPI RSDP to find ACPI tables
    let rsdp = args.acpi_rsdp_base;

    // Use framebuffer for early console
    let fb_addr = args.framebuffer_addr;
    let fb_w = args.framebuffer_width;
    let fb_h = args.framebuffer_height;
}

Structs

KernelArgs

Bootloader-to-kernel handoff structure.

MemoryKind

Memory region type identifier.

MemoryRegion

Memory region descriptor for the bootloader memory map.

Constants

STRAT9_BOOT_ABI_VERSION

ABI version for the boot handoff structure.

STRAT9_BOOT_MAGIC

Magic number validating the boot handoff ("ST9B" in ASCII).