Firmware Interface Table

BIOS Specification October 2022 Revision 1.4

Download as PDF
ID 599500
Date 10/01/2022
Intel Confidential
Document Table of Contents
Document Table of Contents
Legal Firmware Interface Table Introduction Summary of Key Requirements: FIT Pointer Firmware Interface Table
Legal
Firmware Interface Table Introduction
Summary of Key Requirements:
FIT Pointer
FIT Pointer FIT Pointer Rules
FIT Pointer Rules
Firmware Interface Table
Firmware Interface Table FIT Ordering Rules FIT Header (Type 0) Rules Microcode Update (Type 1) Rules Startup ACM (Type 2) Rules Diagnostic ACM (Type 3) Rules Platform Boot Policy (Type 4) Rules FIT Reset State (Type 6) Rules BIOS Startup Module (Type 7) Rules TPM Policy Record (Type 8) Rules BIOS Policy Data Record (Type 9) Rules Intel® TXT Policy Data Record (Type 0xA) Rules Key Manifest Record (Type 0xB) Rules Boot Policy Manifest (Type 0xC) Rules Intel® CSE Secure Boot (Type 0x10) Rules Vendor Authorized Boot Provisioning Table (Type 0x1A) Rules Vendor Authorized Boot Key Manifest (Type 0x1B) Rules Vendor Authorized Boot Image Manifest (Type 0x1C) Rules Vendor Authorized Boot Image Descriptors (Type 0x1D) Rules SACM Debug Record (Type 0x2C) Rules Feature Policy Record (Type 0x2D) Rules Granular SCRTM Error Record (Type 0x2E) Rules
FIT Ordering Rules
FIT Header (Type 0) Rules
Microcode Update (Type 1) Rules
Startup ACM (Type 2) Rules
Diagnostic ACM (Type 3) Rules
Platform Boot Policy (Type 4) Rules
FIT Reset State (Type 6) Rules
BIOS Startup Module (Type 7) Rules
TPM Policy Record (Type 8) Rules
BIOS Policy Data Record (Type 9) Rules
Intel® TXT Policy Data Record (Type 0xA) Rules
Key Manifest Record (Type 0xB) Rules
Boot Policy Manifest (Type 0xC) Rules
Intel® CSE Secure Boot (Type 0x10) Rules
Vendor Authorized Boot Provisioning Table (Type 0x1A) Rules
Vendor Authorized Boot Key Manifest (Type 0x1B) Rules
Vendor Authorized Boot Image Manifest (Type 0x1C) Rules
Vendor Authorized Boot Image Descriptors (Type 0x1D) Rules
SACM Debug Record (Type 0x2C) Rules
Feature Policy Record (Type 0x2D) Rules
Granular SCRTM Error Record (Type 0x2E) Rules
Legal
Firmware Interface Table Introduction
Summary of Key Requirements:
FIT Pointer
Firmware Interface Table

Firmware Interface Table Introduction

This document provides a high-level overview of the Firmware Interface Table.

A Firmware Interface Table (FIT) is a data structure inside BIOS flash and consists of multiple entries. Each entry defines the starting address and attributes of different components in the BIOS. FIT resides in the BIOS Flash area and is located by a FIT pointer at physical address (4GB - 40h), refer to Figure below. The FIT is generated at build time, based on the size and location of the firmware components.

The CPU processes the FIT before executing the first BIOS instruction located at the reset vector (0FFFFFFF0h). If a microcode update for the BSP is pointed by a FIT type 1 entry, it is loaded before executing the BIOS code at the reset vector and applied to all threads within the package.

Refer to the CPU BIOS specification for model specific Microcode Update Loading guidance.

The FIT boot is a method the processors use to establish a root of trust for the BIOS. If a valid type 2 entry is found, then that startup ACM is executed.

For detailed information regarding the ACM, refer to the Intel® Trusted Execution Technology BIOS Specification BIOS Writer's Guide.

Summary of Key Requirements: