Coreboot port almost complete for MSI Pro B850-P AM5 motherboard, current implementation almost boots into Linux

The developers behind coreboot have provided an update on their progress developing a port of the open-source BIOS to a consumer AM5 motherboard, the MSI Pro B850-P. Phoronix reports that 3mdeb, the company behind coreboot, has successfully ported several important blocks required to support AMD (Phoenix) Ryzen 8000 APUs, featuring MPIO, SMU, NBIO, FCH SD, FCH ACPI, and RcMgr. The company also addressed the missing USB initialization code that was causing USB failures to occur on the board previously.

All these changes have made the open-source port almost fully functional, with the team stating that its open-source BIOS implementation now almost makes it to the Linux login screen. In addition to the aforementioned USB fixes, the team also resolved a system hang caused by a bug in the PCIe enumeration process. The main issue that remains is a problem (or problems) surrounding the promontory B850 chipset, causing hard faults to occur.

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Development of this port has taken a couple of months so far, split into multiple parts. Part one involved enabling bootblock and romstage and mapping all of the USB, SATA, and PCIe ports on the motherboard. Part 2 involved adding USB and PCIe devicetree descriptors and integrating Ryzen 8000 series openSIL code into the port.

For those unaware, coreboot is an open-source BIOS alternative that is designed to provide better performance and a smaller footprint compared to outgoing BIOS/UEFI implementations from motherboard makers such as ASUS, GIGABYTE, MSI, and ASRock. Coreboot's design philosophy is to implement the absolute "bare minimum" necessary to ensure hardware is usable, a philosophy that is extremely rare to see in the world of UEFI firmware creation.

coreboot has been around for decades and has been supported largely in Chromebooks, Thinkpads, and older motherboards. It was only recently that coreboot has seen ports into modern consumer desktop motherboards, including the MSI Pro B850-P. One of the first consumer boards to get coreboot support on the Intel side was the Z690-A. The MSI Pro B850-P is the first consumer AM5 motherboard that will support coreboot, an open-source BIOS that is supported on a wide variety of typically older laptops, desktops, and server motherboards.