Specifications

Introduction

1.1 Overview

This specification describes the high-level design of the Compatibility Support Module

(CSM) code that is required for an implementation of the Intel

Platform Innovation

Framework for EFI (hereafter referred to as the "Framework"). The CSM provides

compatibility support between the Framework and traditional, legacy BIOS code and

allows booting a traditional OS or booting an EFI OS off a device that requires a

traditional option ROM (OpROM). This specification does the following:

• Describes the basic components of the CSM

• Defines how to use traditional BIOS option ROMs (OpROMs) to boot an EFI

operating system (OS)

• Defines how to boot a traditional OS

• Provides code definitions

for compatibility-related services, protocols,

functions, and type definitions that are architecturally required by the Intel

Platform Innovation Framework for EFI Architecture Specification

1.2 Scope

This document describes the high-level design of the Compatibility Support Module

(CSM) code developed for the Intel

Platform Innovation Framework for EFI (hereafter

referred to as "the Framework"). This document will define how to do the following:

• Use traditional BIOS option ROMs (OpROMs) to boot an EFI Operating

System (OS)

• How to boot a traditional OS

This document’s primary focus is how to bind EFI and compatibility support code

together. It does not define internal details of the CSM design

1.3 Rationale

There is always a transitional period between the introduction of a new technology and

the technology that it replaces. The addition of compatibility support code to EFI bridges

this transitional period. The compatibility support code allows booting a traditional OS or

booting an EFI OS off a device that requires a traditional OpROM.