Bootloader Documentation

See also: Home, Developer Guide, Roadmap

This is the documentation about the bootloader of Valecium OS.

Current Status

The custom bootloader is under development. Currently:

BIOS i686 stage1 (boot.S): MBR bootsector that loads stage2 via INT 13h LBA — implemented
BIOS i686 stage2 (core.S): Transitions to protected mode (A20 gate, GDT, CR0) — implemented but does not yet load the kernel
BIOS x86_64: Stub only
EFI (i686/x86_64/aarch64): Stubs only
Common code (hal.c, filesystems.c): Empty placeholders

The default boot method uses GRUB (installed from the host system), which handles kernel loading via multiboot. The custom bootloader (BootSystem=system) is built but not yet functional for kernel loading.

Boot Processes

BIOS Boot Process — The boot process that the BIOS uses to load the kernel
EFI Boot Process — The process that EFI bootloader uses to load

Build

The bootloader is built via SCons:

scons BootType=bootloader
# or as part of full build:
scons BootSystem=system

Output: * boot.bin — Stage1 MBR boot sector (raw binary, 512 bytes) * core.bin — Stage2 protected mode loader (raw binary) * boot.efi — EFI bootloader (not yet functional)

Revision History

v2.0

Updated for v0.28: added current status section describing actual implementation state, build instructions, output files

v1.0

Added the boot process maps.