Arm has published its PC Base System Architecture (PC-BSA) specification, the blueprint for standardizing Arm-based PCs.
The spec, which is an extension of its broader Base System Architecture (BSA), sets out the hardware and firmware requirements to make Arm systems more predictable for operating systems, hypervisors, and other software.
At its heart, PC-BSA Level 1 demands that 64-bit processors be built on Armv8.1 or newer, the integration of the Trusted Platform Module (TPM) 2.0 for more secure hardware-backed features, System Memory Management Unit (SMMU) support to enable virtualization, and adherence to PCI Express standards for consistent device compatibility.
These are all essentially designed to reduce the hardware quirks that have plagued compatibility with Arm systems within the x86 arena, ensuring secure boot processes and compatibility with modern software out-of-the-box.
Virtualization gets a lot of focus, with SMMU support baked into the requirements to handle memory management consistently and make device assignment practical within virtualized environments. From the first iteration of the PC-BSA, it seems that Arm PCs are being shaped to meet today's demands, where virtual machines and containers are essential for dividing and managing workloads.
On the security front, the inclusion of TPM 2.0 and secure boot isn't just ticking a regulatory box - it's a step toward giving Arm systems the same credibility as x86 in industries with tight compliance standards. For reference, TPM 2.0 is a requirement to run Microsoft's Windows 11 operating system.
PCIe compliance is another crucial piece, aimed at ensuring Arm PCs can handle and remain compatible with modern hardware like GPUs and fast storage with fewer headaches. Standardizing this also ensures developers know what to expect, while OEMs get an easier ride when piecing together systems without the need for intricate fixes for each configuration.
Level 1 lays down the basics, but there is more to come. Future compliance levels promise fancier tools, such as memory tagging to simplify debugging and error isolation, as well as more comprehensive cryptography support to keep things watertight. These extras are designed to expand the role of Arm machines within the broader PC landscape, but the PC-BSA leaves plenty of room for the spec to evolve as demands get tougher within future levels and iterations.
Essentially, the PC-BSA lays a solid foundation, but the success depends on its adoption rate. History is full of well-meaning standards that never made it past the PDF stage, but for now, Arm has laid out the rules. It's now up to OEMs and developers to decide if they want to join the Windows on Arm revolution. ®