80x86 Boot State Specifications

BCOS Boot Catalogue Specification
BCOS Transition State 1 Specification
BCOS Transition State 2 Specification
Common PC BIOS Module Transition State Specification

There's several stages used during boot, and several specifications that describe the state the computer must be in before moving from one stage to another. This allows anyone to write new modules for any stage that complies with the relevant specification/s, and know that their new module will work with all existing modules.

Software/Main Module

Specification

Stage 0

Boot environment

Not part of the OS

Boot environment startup state

Stage 1

Boot Loader

Depends on type of boot environment, and in some cases (e.g. PC BIOS) the type of boot device

Common PC BIOS Module Transition State Specification (PC BIOS only)

Stage 1.5

Common PC BIOS Module (PC BIOS only)

Used to reduce the code needed in each boot loader that is designed for the PC BIOS. Boot loaders for other boot environments go directly from Stage 1 to Stage 2 and skip stage 1.5

BCOS Transition State 1 Specification

Stage 2

Stage 2 Manager

Does not depend on boot environment or kernel type

BCOS Transition State 2 Specification

Stage 3

Kernel Setup Module

Depends on kernel type

Table 1 - Boot States

Generated on Tue Sep 15 20:20:49 2009