A quiet milestone in the world of open-source firmware has been reached. 3mdeb’s Dasharo project has successfully ported coreboot with AMD openSIL to boot Windows 11 without any workarounds on the MSI PRO B850-P WiFi, a readily available AM5 motherboard designed for Ryzen processors. This achievement, first reported by Phoronix on July 3, 2026, slashes through years of compatibility barriers that had kept open firmware enthusiasts from running Microsoft’s latest operating system on modern AMD hardware.

For years, the dream of a fully open-source boot stack on consumer x86 machines has felt tantalizingly close yet frustratingly out of reach. Coreboot, the lean and lightning-fast firmware replacement, has long powered Chromebooks and server farms, but desktop users—especially those wanting Windows—have faced a gauntlet of hacks, shims, and fragile workarounds. The arrival of AMD’s openSIL (Open Silicon Initialization Library) promised a cleaner path, replacing the aging AGESA with transparent, auditable code. Now, Dasharo has turned that promise into something tangible.

The Coreboot Conundrum on Windows

Coreboot itself is not a BIOS but a minimal firmware initialization framework. It hands over hardware control to a payload, such as TianoCore EDK II (the open-source UEFI implementation) or a Linux kernel. For Windows, UEFI compliance is mandatory—especially for Windows 11, which enforces Secure Boot and TPM 2.0 requirements. While coreboot plus TianoCore can theoretically boot Windows, the devil has always been in the silicon initialization details. AMD’s traditional AGESA (AMD Generic Encapsulated Software Architecture) is a binary blob that handles complex memory training, PCIe configuration, and power management. Reverse-engineering or clean-room implementing those routines is a monumental task, and previous coreboot ports for AMD platforms often relied on extracting AGESA binaries from the vendor BIOS—a legally gray and technically brittle approach.

Enter openSIL. Announced by AMD in 2023, openSIL is a set of open-source libraries intended to replace AGESA in stages. The initial versions provide memory initialization and basic hardware setup, with more features rolling out over time. By the time AMD’s Zen 5 (Granite Ridge) and AM5 infrastructure matured, openSIL had reached a level of completeness where booting a full OS was plausible—but no one had publicly demonstrated a clean, blob-free Windows 11 boot on a retail AM5 board until now.

Dasharo: Polishing Coreboot for the Masses

Dasharo, developed by 3mdeb, is a distribution of coreboot that emphasizes security, ease of use, and modern features. It ships with a graphical configuration tool, automated updates, and first-class support for TianoCore payloads. The team has previously brought coreboot to Intel platforms like the MSI Z690-A and several Protectli vaults, but AMD support has been a long-standing goal. With openSIL maturing, the Dasharo crew turned their attention to the MSI PRO B850-P WiFi, a mid-range motherboard based on the AMD B650 chipset (the B850P is a cost-optimized variant). The choice was strategic: it’s a popular board with good community penetration, and its UEFI implementation is well-documented.

The build that achieved the breakthrough uses coreboot as the initial program loader, AMD openSIL libraries for DRAM training and platform initialization, and a Dasharo-customized TianoCore payload that presents a fully UEFI-compliant interface to the OS. Critically, it supports Secure Boot with a default set of keys, meets TPM 2.0 requirements via the firmware TPM (fTPM) built into Ryzen processors, and handles ACPI table generation correctly. Previous attempts often stumbled on ACPI quirks that caused Windows 11 installers to bluescreen or hang; Dasharo’s meticulous table crafting has ironed out those wrinkles.

Booting Windows 11: No Shims, No Patches

What sets this milestone apart is the absence of workarounds. Earlier experiments with coreboot on AMD AM4 platforms required booting through GRUB as an intermediate stage, or injecting custom DSDT overrides, or even patching the Windows kernel to ignore ACPI malformations. The Dasharo implementation is a drop-in replacement for the proprietary MSI firmware. Fire up the board, press F11 for the boot menu, and the Windows 11 installation media boots as if it were a factory UEFI. Once installed, the OS runs with full hardware acceleration, including the integrated GPU (if present), NVMe drives, and all USB ports.

Under the hood, openSIL handles the heavy lifting of initializing the CPU complex, the memory controller, and the chipset links. Dasharo’s coreboot then hands off to the DXE phase of TianoCore, which loads Windows Boot Manager. Because openSIL is built from source and included as part of the coreboot tree, the entire firmware binary can be compiled without any proprietary binaries—something that should delight organizations concerned about supply chain security and regulatory compliance.

Why the MSI PRO B850-P WiFi Matters

The choice of board is no accident. The MSI PRO B850-P WiFi is a consumer-focused AM5 motherboard that supports Ryzen 7000, 8000, and 9000 series processors. It offers PCIe 5.0, DDR5 memory, and WiFi 6E, making it a representative platform for modern desktops. Its UEFI firmware is based on AMI’s Aptio, a widely used codebase that coreboot developers have studied extensively. The board also has a dual-BIOS feature, which makes it safer for enthusiasts to flash experimental firmware without bricking their systems permanently.

By targeting a popular consumer board, 3mdeb and the Dasharo community are signaling that open firmware is not just for niche embedded devices or high-end servers—it can be practical for the PC you build at home. The implications ripple across several domains:

  • Security and Transparency: With openSIL, security researchers can audit the code that initializes the processor and chipset, uncovering potential vulnerabilities before they become exploits. Governments and enterprises with strict firmware security mandates can verify that no backdoors exist.
  • Longevity and Right to Repair: Proprietary UEFI updates eventually dry up when vendors move on. Coreboot with openSIL can be maintained and updated by the community indefinitely, breathing new life into older hardware.
  • Performance Tuning: Coreboot boots in a fraction of the time of traditional UEFI. By stripping out unnecessary blobs and optimizing memory training routines, Dasharo can significantly reduce POST times. Early numbers from the project suggest boot times under two seconds from power-on to Windows logo.
  • Cross-OS Compatibility: While the current achievement centers on Windows 11, the same firmware can boot Linux, BSD, or even bare-metal hypervisors without modification, making it an ideal choice for dual-boot systems or development workstations.

The Road to This Moment

The journey to Windows 11 on open firmware has been years in the making. AMD first detailed openSIL at the 2023 OCP Summit, with plans to phase out AGESA for server platforms (EPYC) initially and then extend to client APUs. In 2024, the coreboot project merged initial support for AMD’s Genoa and Bergamo server chips, but client AM5 support lagged due to missing motherboard-specific code. The Dasharo team began experimenting with openSIL in early 2025, posting progress reports on their blog and community forums. By late 2025, they had Linux booting stably on the MSI board. The final push for Windows 11 involved painstaking ACPI debugging, often with the help of Microsoft’s Windows Hardware Lab Kit (HLK) to validate compliance.

Phoronix’s July 2026 report notes that the firmware is still considered a developer preview. Memory compatibility is good but not universal—certain high-speed DDR5 kits may require manual tuning. Resume from S3 sleep is functional but occasionally stalls, and the integrated audio codec still needs a proprietary verb table extracted from the original firmware (though the team is working on a free replacement). Despite these rough edges, the fact that Windows 11 installs and runs daily workloads without crashes is a testament to the maturity of openSIL.

Challenges Ahead

While this achievement is groundbreaking, it’s not a plug-and-play solution for the average user yet. Several hurdles remain:

  • Hardware Compatibility: Each motherboard model requires its own coreboot port. Even within the AM5 ecosystem, the I/O layout, VRM controllers, and Super I/O chips differ. Dasharo currently supports only one board, and extending to others will take time and community contributions.
  • UEFI Advanced Features: Vendor firmware often includes elaborate overclocking menus, RGB lighting control, and fan curve utilities that are absent from Dasharo. Enthusiasts who value these features may find the open firmware spartan.
  • AMD’s Code Quality and Update Cadence: OpenSIL is still relatively new, and AMD’s release cycle for the libraries does not align perfectly with coreboot’s upstream. Dasharo has to carry patches to bridge the gap, and there’s a risk of breakage with new CPU steppings.
  • Secure Boot Key Management: While Dasharo supports Secure Boot, managing custom keys or dual-booting with Linux distributions that shim into the Microsoft key hierarchy can be confusing for end users.
  • General Support and Documentation: To attract non-developers, Dasharo will need polished installers, clear guides, and perhaps a warranty-safe flashing method (like using MSI’s M-Flash utility).

Community and Industry Reaction

The open-source firmware community has greeted the news with enthusiasm. On forums like r/coreboot and the Dasharo mailing list, users are already asking about porting efforts for the ASUS ROG STRIX B650 and Gigabyte X670E. Some have offered to donate hardware or sponsor development. 3mdeb has hinted that corporate clients are interested in using Dasharo for air-gapped Windows workstations that require verified firmware integrity.

From a broader industry perspective, this milestone puts pressure on motherboard vendors to consider offering coreboot as an official option. Framework Computer’s modular laptops already ship with coreboot on Intel variants, and AMD’s decision to fund openSIL development signals a strategic shift. If Windows 11 boots reliably, the last major objection from PC OEMs—the “no Windows” barrier—starts to crumble.

What This Means for Windows Users

For the millions of Windows users who have never heard of coreboot, the immediate impact is minimal. But the long-term implications are profound. A competitive, open firmware ecosystem could break the duopoly of AMI and Insyde, potentially lowering licensing costs for board makers and resulting in more frequent security updates. It also aligns with Microsoft’s own push for Secure Core PCs, where firmware integrity is a foundational requirement. In a future where Windows 12 or beyond demands even stricter hardware attestation, having a transparent firmware stack might become a differentiator rather than a niche geek curiosity.

Perhaps most exciting is the potential for enthusiast innovation. Once the coreboot+openSIL codebase stabilizes, tinkerers can experiment with exotic payloads—booting directly into a hypervisor for GPU passthrough, for example, or integrating a lightweight Linux kernel that runs before Windows to provide advanced power management. The boundary between boot firmware and operating system becomes a canvas.

How to Try It

Adventurous users can download the Dasharo binary and source code from the project’s Git repository. Flashing requires a USB drive and MSI’s built-in Flash BIOS Button, which can recover from a bad flash as long as the bootblock remains intact. The team advises starting with a minimal configuration (one RAM stick, no exotic PCIe cards) and gradually adding components. Full installation instructions are on the Dasharo wiki, and the community forums offer troubleshooting assistance. As always, trying pre-release firmware on your primary machine carries risks; a dedicated test bench or a second BIOS chip is the safest approach.

Looking Forward

The Dasharo team is not resting. Plans are already in motion to upstream the MSI board support into coreboot’s main branch, which would allow other distributions like MrChromebox’s firmware or custom builds to benefit. AMD is expected to release openSIL v2.0 later in 2026, adding USB4 and PCIe 6.0 initialization, which will further close the feature gap with AGESA. If all goes well, we might see a wave of AM5 boards with community-supported coreboot ports by the end of the year.

In the grand narrative of personal computing, this moment marks a turning point. What was once a hobbyist’s pipe dream—running a modern Windows OS on fully open firmware—is now a working reality. The software stack that turns a pile of silicon into a functioning PC can finally be inspected, modified, and trusted. For Windows enthusiasts tired of opaque firmware updates and mysterious performance regressions, Dasharo and openSIL offer a refreshing alternative. The ignition sequence of the PC has never been more transparent.