Appendix G: Alternative Firmware Approaches

Overview of open-source firmware alternatives to proprietary UEFI implementations.

Introduction

While this guide focuses on UEFI development using EDK2, the firmware ecosystem includes several alternative approaches. Understanding these alternatives helps you choose the right solution for your platform and recognize how they interoperate with UEFI.

Why Consider Alternatives?

Concern UEFI (Proprietary) Open-Source Alternatives
Code Auditability Closed-source vendor code Fully auditable source
Attack Surface Large codebase (~millions of lines) Minimal, focused code
Boot Speed Slower (feature-rich) Faster (minimal)
Customization Vendor-dependent Full control
Security Updates At vendor’s convenience Community-driven
Binary Blobs Required (FSP, AGESA) Varies by project

Comparison Matrix

Project Language x86 Support ARM Support RISC-V Binary Blobs UEFI Compatible
coreboot C Yes Limited Yes Some required Via payload
LinuxBoot Go/C Yes Yes Yes Host-dependent Replaces DXE
AMD openSIL C AMD only No No None (goal) Yes
oreboot Rust No Yes Yes None Via payload
Libreboot C Yes Limited No None Via payload 
graph TB
    subgraph "Traditional UEFI Boot"
        SEC1[SEC] --> PEI1[PEI]
        PEI1 --> DXE1[DXE]
        DXE1 --> BDS1[BDS]
        BDS1 --> OS1[OS Loader]
    end

    subgraph "coreboot Boot"
        CB_BOOT[Bootblock] --> CB_ROM[Romstage]
        CB_ROM --> CB_RAM[Ramstage]
        CB_RAM --> CB_PAY[Payload]
        CB_PAY --> OS2[OS/UEFI/Linux]
    end

    subgraph "LinuxBoot"
        LB_PEI[UEFI PEI/coreboot] --> LB_LINUX[Linux Kernel]
        LB_LINUX --> LB_UROOT[u-root initramfs]
        LB_UROOT --> OS3[kexec to OS]
    end

    style SEC1 fill:#2196f3
    style CB_BOOT fill:#4caf50
    style LB_LINUX fill:#ff9800

coreboot

Overview

coreboot (formerly LinuxBIOS) is an open-source firmware project that replaces proprietary BIOS/UEFI with minimal code to initialize hardware. It focuses on doing “just enough” to hand off to a payload (bootloader, OS, or UEFI environment).

Design Philosophy

  • Minimal: Only initialize hardware necessary for the payload
  • Fast: Boot times under 1 second for desktops, minutes saved on servers
  • Auditable: Open-source code with reduced attack surface
  • Payload-agnostic: Can launch SeaBIOS, GRUB, Linux, or even TianoCore UEFI

Architecture

Stage Purpose Size (typical)
Bootblock CPU reset, CAR setup, load romstage ~20KB
Romstage Memory init, early hardware ~87KB (native)
Ramstage Device enumeration, resource allocation ~200KB
Payload Bootloader/OS/UEFI Varies

Current State (2025-2026)

  • Latest Release: coreboot 25.12 (December 2025)
  • Next Release: 26.03 (March 2026)
  • Active Development: 50+ contributors, regular releases
  • Production Use: Google Chromebooks, System76, Purism, Protectli

Platform Support

Vendor Platforms Notes
Intel Many generations FSP binary required
AMD Select platforms AGESA/openSIL
ARM Limited Primarily development boards
RISC-V Growing SiFive, StarFive

UEFI Interoperability

coreboot can launch a TianoCore EDK2 payload, providing full UEFI boot services:

graph LR
    CB[coreboot<br/>hardware init] --> EDK2[EDK2 Payload] --> OS[UEFI Applications/OS]
    style CB fill:#4caf50
    style EDK2 fill:#2196f3

This gives you coreboot’s fast, auditable init with UEFI compatibility.

Key Resources

Resource Link
Official Site coreboot.org
Documentation doc.coreboot.org
Tutorial Tutorial Part 1
GitHub github.com/coreboot/coreboot
IRC #coreboot on Libera.Chat

LinuxBoot

Overview

LinuxBoot replaces specific UEFI firmware functionality with a Linux kernel and initramfs. Instead of running UEFI DXE drivers for storage, network, and other devices, LinuxBoot uses proven Linux drivers.

Design Philosophy

  • Replace, Don’t Rewrite: Use Linux’s battle-tested drivers instead of UEFI DXE
  • Reduce Attack Surface: Replace millions of lines of UEFI with audited Linux kernel
  • Standardized Environment: Developers work in familiar Linux userspace
  • Flexible Boot: Boot via kexec, network (PXE/HTTP), or local storage

Architecture 

graph LR
    subgraph "Host Firmware"
        HW[Hardware Init] --> |"UEFI PEI or coreboot"| MEM[Memory Ready]
    end

    subgraph "LinuxBoot"
        MEM --> KERNEL[Linux Kernel]
        KERNEL --> INITRD[u-root initramfs]
        INITRD --> BOOT[systemboot/localboot/netboot]
    end

    subgraph "Target"
        BOOT --> |kexec| TARGET[Production OS Kernel]
    end

    style KERNEL fill:#ff9800
    style INITRD fill:#ff9800

Components

Component Description
Linux Kernel Minimal kernel for hardware access (~5MB)
u-root Go-based initramfs with Unix utilities
systemboot Boot logic (netboot, localboot) merged into u-root

Current State (2025-2026)

  • Active Development: Supported by Google, Meta, and others
  • Production Use: Large-scale data center deployments
  • u-root: Actively maintained, Go 1.21+ required
  • Documentation: LinuxBoot Book

Advantages Over Traditional UEFI

Aspect UEFI DXE LinuxBoot
Driver Quality Vendor-specific, closed Linux mainline, audited
Network Boot PXE (limited) Full HTTP/HTTPS, SSH
Debugging Proprietary tools Standard Linux tools
Updates Flash firmware Update kernel/initrd
Security Varies Kernel security features

Key Resources

Resource Link
Official Site linuxboot.org
LinuxBoot Book book.linuxboot.org
u-root GitHub github.com/u-root/u-root
Coreboot Integration book.linuxboot.org/coreboot.u-root.systemboot

AMD openSIL

Overview

AMD openSIL (Open Silicon Initialization Library) is AMD’s initiative to replace the closed-source AGESA firmware with an open-source silicon initialization library. It represents a major shift toward transparency in x86 firmware.

Design Philosophy

  • Host-Agnostic: Works with UEFI, coreboot, oreboot, or any host firmware
  • Open Source: Full source code under MIT license (when released)
  • Modern Architecture: Written in C17, clean API design
  • Scalable: Same codebase for client and server platforms

Architecture

openSIL consists of three statically linked libraries:

Library Purpose
xSIM Silicon Initialization - CPU, memory controller, I/O
xPRF Platform Reference - Board-specific customizations
xUSL Utilities & Services - Common helper functions 
graph TB
    subgraph "Host Firmware"
        HOST[UEFI / coreboot / oreboot]
    end

    subgraph "AMD openSIL"
        xSIM[xSIM - Silicon Init]
        xPRF[xPRF - Platform]
        xUSL[xUSL - Utilities]
    end

    HOST --> |"API Calls"| xSIM
    HOST --> |"API Calls"| xPRF
    xSIM --> xUSL
    xPRF --> xUSL

    style xSIM fill:#ed1c24
    style xPRF fill:#ed1c24
    style xUSL fill:#ed1c24

Current State (2025-2026)

Milestone Status
Proof-of-Concept (Genoa) Complete
Extended POC (Turin/Phoenix) Complete
Production openSIL (Venice/Medusa) 2026
Open-source release Q3-Q4 2026
AGESA End of Life 2026

2026 Transition: AMD has confirmed that AGESA will be end-of-life in 2026, with openSIL replacing it for all new products. The first production platforms will be 6th Gen EPYC “Venice” (server) and Ryzen “Medusa” (client).

Comparison: AGESA vs openSIL

Aspect AGESA openSIL
Source Closed binary blob Open source (MIT)
Host Support UEFI only Any host firmware
Build Time 20-30 minutes ~30 seconds
Auditability None Full
Integration Binary linking Static source linking

Industry Adoption

  • 9elements: Collaborating with AMD on coreboot integration
  • MiTAC: Experimenting with openSIL POC
  • Supermicro: Evaluating for server platforms
  • NLnet Foundation: Funding coreboot+openSIL for modern AMD boards

Key Resources

Resource Link
AMD Blog AMD openSIL Announcement
GitHub (POC) github.com/openSIL/openSIL
Basic Input/Output Blog AMD openSIL Analysis
OSFC Talks Open Source Firmware Conference

oreboot

Overview

oreboot is a fork of coreboot rewritten entirely in Rust, with no C code. It targets platforms that can be fully open-source without binary blobs.

Design Philosophy

  • No C Code: Memory-safe Rust throughout
  • No Binary Blobs: Only truly open hardware supported
  • LinuxBoot Payload: Designed specifically for LinuxBoot
  • Modern Development: GitHub-based, auto-formatted code

Current State (2025-2026)

Aspect Status
x86 Support None (blobs required)
ARM Support AST2500 BMC
RISC-V Support SiFive HiFive Unleashed
Maturity Experimental

Supported Platforms

Platform Architecture Notes
AST2500 ARM BMC platform
HiFive Unleashed RISC-V SiFive development board
QEMU Various For testing

Key Resources

Resource Link
GitHub github.com/oreboot/oreboot
Documentation In repository README

Libreboot & Canoeboot

Overview

Libreboot and Canoeboot are coreboot distributions that provide pre-built, tested firmware images for specific hardware. They focus on user accessibility - you don’t need to be a firmware developer to install them.

Differences

Aspect Libreboot Canoeboot
Philosophy Pragmatic blob policy Strictly libre (no blobs)
CPU Microcode Included when beneficial Excluded
Hardware Support Broader More restricted
Target Users Security-conscious users Free software purists

Current State (2025-2026)

  • Latest Release: 26.01 (January 2026)
  • SPI Membership: Libreboot became an SPI Associated Project (September 2025)
  • Active Maintenance: Regular releases tracking coreboot upstream

Supported Hardware (Examples)

Category Devices
Laptops ThinkPad X200, T400, Dell Latitude E7240
Desktops HP Pro 3500, various AMD boards
Servers ASUS KGPE-D16, KFSN4-DRE

Installation

Unlike coreboot (which requires compilation), Libreboot/Canoeboot provide ready-to-flash ROM images:

# Example: Flash internally (if supported)
flashrom -p internal -w libreboot.rom

# Example: Flash externally via SPI programmer
flashrom -p ch341a_spi -w libreboot.rom

Hardware Risk: Flashing firmware incorrectly can brick your device. External flashing equipment may be needed for recovery.

Key Resources

Resource Link
Libreboot libreboot.org
Canoeboot canoeboot.org
Installation Guide libreboot.org/docs/install
Downloads libreboot.org/download
Purchase Pre-installed Minifree Ltd

Integration Patterns

coreboot + UEFI Payload

Use coreboot for fast, auditable hardware init, then launch EDK2 for UEFI compatibility:

graph TB
    subgraph coreboot["coreboot"]
        BB[Bootblock<br/>reset] --> RS[Romstage<br/>memory]
        RS --> RAM[Ramstage<br/>devices]
        RAM --> EDK2[EDK2 Payload<br/>UEFI DXE+BDS]
    end

    EDK2 --> OS[UEFI Applications / OS]

    style BB fill:#4caf50
    style RS fill:#4caf50
    style RAM fill:#4caf50
    style EDK2 fill:#2196f3

LinuxBoot with UEFI PEI

Keep UEFI PEI for silicon init, replace DXE with LinuxBoot:

graph TB
    subgraph UEFI_PEI["UEFI PEI Phase"]
        SEC[SEC] --> PEI[PEI]
        PEI --> MEM[Memory/Silicon<br/>Initialization]
    end

    subgraph LB["LinuxBoot"]
        KERNEL[Linux Kernel] --> UROOT[u-root<br/>initramfs]
        UROOT --> SYSBOOT[systemboot<br/>boot logic]
    end

    MEM --> KERNEL
    SYSBOOT --> OS[kexec to Target OS]

    style SEC fill:#2196f3
    style PEI fill:#2196f3
    style MEM fill:#2196f3
    style KERNEL fill:#ff9800
    style UROOT fill:#ff9800
    style SYSBOOT fill:#ff9800

AMD openSIL with Host Firmware

openSIL provides silicon init as a library for any host:

graph TB
    subgraph HOST["Host Firmware (UEFI/coreboot/oreboot)"]
        subgraph OPENSIL["AMD openSIL Libraries"]
            xSIM[xSIM<br/>Silicon]
            xPRF[xPRF<br/>Platform]
            xUSL[xUSL<br/>Utilities]
        end
        CONTINUE[Host continues with<br/>DXE/ramstage/etc.]
    end

    xSIM --> xUSL
    xPRF --> xUSL
    OPENSIL --> CONTINUE

    style xSIM fill:#ed1c24
    style xPRF fill:#ed1c24
    style xUSL fill:#ed1c24

Choosing the Right Approach

Decision Guide

If you need… Consider…
Maximum UEFI compatibility EDK2 (this guide) or coreboot + EDK2 payload
Fast boot, auditable code coreboot
Data center scale, Linux expertise LinuxBoot
AMD platforms, future-proof openSIL (when available)
Memory-safe firmware, no blobs oreboot (limited platforms)
Ready-to-use libre firmware Libreboot/Canoeboot

Platform Considerations

Platform Recommended Approach
Intel Client/Server coreboot + FSP, or LinuxBoot
AMD Client (current) coreboot + AGESA
AMD Server (2026+) openSIL + host of choice
ARM Server LinuxBoot or TF-A + EDK2
RISC-V oreboot or coreboot
Chromebook coreboot (factory default)

Community and Events

Conferences

Event Description
OSFC Open Source Firmware Conference - annual gathering
OCP Summit Open Compute Project - AMD openSIL updates
Embedded Linux Conference LinuxBoot presentations

Organizations

Organization Focus
Open Source Firmware Foundation Advocacy and coordination
CHIPS Alliance Open-source hardware/firmware
RISC-V International RISC-V ecosystem

Getting Involved

Project How to Contribute
coreboot Gerrit code review, IRC
LinuxBoot GitHub PRs, Slack
openSIL GitHub (when public)
oreboot GitHub PRs
Libreboot Git patches, IRC

Summary

The firmware landscape is evolving rapidly. While proprietary UEFI remains dominant, open-source alternatives offer compelling benefits:

  • coreboot provides a mature, production-ready alternative for many platforms
  • LinuxBoot brings Linux’s robust driver ecosystem to firmware
  • AMD openSIL promises fully open silicon init for AMD platforms starting 2026
  • oreboot explores memory-safe firmware in Rust
  • Libreboot/Canoeboot make open firmware accessible to non-developers

For UEFI developers, understanding these alternatives helps you:

  1. Choose the right foundation for new projects
  2. Integrate open firmware with UEFI when needed
  3. Prepare for the industry’s shift toward openness

This appendix provides an overview. For hands-on development, refer to each project’s official documentation linked above.

Additional Resources

Comparison Articles

Video Presentations

  • OSFC talks (available on YouTube)
  • OCP Summit AMD openSIL sessions
  • Google Tech Talks on LinuxBoot

Mailing Lists

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