Unified Extensible Firmware Interface (UEFI) is gradually replacing the traditional system BIOS. The vast majority of PCs on the market are now based on UEFI technology, and a number of these include what is called a Compatibility Support Module (CSM). This CSM “layer” replaces the traditional BIOS and provides backward-compatibility support for booting operating systems such as DOS, OS/2, and, of course,ArcaOS. (This is typically listed as “Compatibility”, or “Legacy” boot in the system setup menu of UEFI-based PCs.)

PC manufacturers and Intel specifically have stated publicly that they intend to phase out inclusion of a CSM layer in the next few years (in the case of Intel, beginning in 2020), leaving UEFI as the only boot option, eliminating the “Compatibility” selection. To prepare for this, Arca Noae has been exploring ways to boot ArcaOS on systems lacking a manufacturer-supplied CSM. We are pleased to announce that over the last several months our development team has made significant progress in achieving that goal.

In the lab, we are now able to boot ArcaOS all the way to a desktop on a system configured to boot in UEFI mode. All necessary drivers load, with all CPU cores running, and ArcaOS properly switches to graphics mode. The importance of this accomplishment cannot be understated. To our knowledge, this is the first time ArcaOS has ever booted without the presence of an active CSM.

Having said that, this project is still in its research stage and not yet ready for release to our beta testers. Native UEFI support requires changes to the low level disk and video subsystems, and this work is ongoing.

We remain cautiously optimistic that we will complete our Proof of Concept successfully and will have a UEFI solution for a future ArcaOS version.

Oh, and Arca Noae has been an Adopting member of the UEFI Forum since 2015.