ACPI Specification Now Managed By UEFI, and Why Anyone Should Care

This article by my UEFI colleagues Dong Wei (HP, VP of UEFI) and Andrew Sloss (ARM, ARM Binding Sub-Team Chair) talks about a large recent development in the firmware world: ACPI is now managed by UEFI. I was a part of the ACPI specification development starting with ACPI 2.0 up through the current ACPI 5.0 specification while I was employed with Phoenix Technologies. That specification seems unusual to me now, in that it was essentially a five-way agreement between Intel, Microsoft, Compaq/HP, Phoenix and Toshiba. But actually, back in the day when it was conceived, it wasn't that unusual, as the BIOS Boot Specification (BBS) or Advanced Power Management (APM) will attest. For every revision of the specification, essentially the 5-way consortium was reborn again, occasionally (such as when Phoenix was added or Compaq was merged with HP) with a change of membership.

Due to the unusual structure and the fact that it was tied in many ways to Microsoft's release schedule and Intel's hardware schedule, releases tended to be big and cumbersome. Adding new members was problematic, since the number of signatures required from legal departments grows exponentially.

On the other hand, UEFI has functioned pretty well since 2005 in taking input, releasing regular errata and specification updates. So with Mark Doran (Intel, UEFI president) assuming the helm of both efforts, it seemed like a good time to push them together. They really address the same target audiences: system firmware providers, OS vendors, OEMs and chip manufacturers, with a smattering of plug-in card and application vendors. It probably helps convince folks like Linaro (working on ARM) and Redhat (working on Linux) to adopt ACPI if more than Intel and Microsoft are represented.

Now the process that is used to gather input, hash out differences and formulate solutions for UEFI can be applied to ACPI with, in my opinion, great effect.