Overview

Currently we boot from BIOS on a GPT-partitioned disk.

boot0.s is the first-stage bootloader. It lives in the MBR bootstrap field, and must therefore fit into 440 bytes. Its tasks are:

• Set up a stack etc.
• Get the boot drive geometry
• Load and parse the GPT
• Find the partition of the second stage
• Load and jump to the first sector of the second stage

boot1.s is the second-stage bootloader. Its tasks are:

• Load its own sectors not loaded by the first stage
• Enable A20
• Detect available memory
• Enter unreal mode
• Read the kernel ELF from disk (don't have to parse the ELF just yet)
• Get all the useful information we can from the BIOS before we leave unreal mode
• Enter long mode (possibly via protected mode?)
• Load the kernel ELF
• Initialise stack etc. for the kernel
• Jump to kernel