ACPIspec10.pdf

The Advanced Configuration and Power Interface (ACPI) specification is the key element in Operating System Directed Power Management (OSPM). OSPM and ACPI both apply to all classes of computers, explicitly including desktop, mobile, home, and server machines. ACPI evolves the existing collection of power management BIOS code, APM APIs, PNPBIOS APIs, and so on into a well-specified power management and configuration mechanism. It provides support for an orderly transition from existing (legacy) hardware to ACPI hardware, and it allows for both mechanisms to exist in a single machine and be used as needed. Further, new system architectures are being built that stretch the limits of current Plug and Play interfaces. ACPI evolves the existing motherboard configuration interfaces to support these advanced architectures in a more robust, and potentially more efficient manner. This document describes the structures and mechanisms necessary to move to operating system (OS) directed power management and enable advanced configuration architectures — that is, the structures and mechanisms necessary to implement ACPI-compatible hardware and to use that hardware to implement OSPM support.