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Overall design decision was not without criticism. At the BIOS development time, AML bytecode is compiled from the ASL (ACPI Source Language) code. A reference AML interpreter implementation is provided by the ACPI Component Architecture (ACPICA). To make use of the ACPI tables, the operating system must have an interpreter for the AML bytecode. Much of the firmware ACPI functionality is provided in bytecode of ACPI Machine Language (AML), a Turing-complete, domain-specific low-level language, stored in the ACPI tables. The ACPI BIOS generates ACPI tables and loads ACPI tables into main memory. The firmware-level ACPI has three main components: the ACPI tables, the ACPI BIOS, and the ACPI registers. The UEFI Forum published the latest version of the standard, 'Release 6.5' in August 2022. In October 2013, ACPI Special Interest Group (ACPI SIG), the original developers of the ACPI standard, agreed to transfer all assets to the UEFI Forum, in which all future development will take place. Intel, Microsoft and Toshiba originally developed the standard, while HP, Huawei and Phoenix also participated later. ACPI then executes the desired operations written in ACPI Machine Language (such as the initialization of hardware components) using an embedded minimal virtual machine. Internally, ACPI advertises the available components and their functions to the operating system kernel using instruction lists (' methods') provided through the system firmware ( UEFI or BIOS), which the kernel parses. BIOS, UEFI), the computer hardware components, and the operating systems. ACPI defines hardware abstraction interfaces between the device's firmware (e.g. The specification is central to the Operating System-directed configuration and Power Management ( OSPM) system. ACPI brings power management under the control of the operating system, as opposed to the previous BIOS-centric system that relied on platform-specific firmware to determine power management and configuration policies. First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification. Plug and Play and hot swapping), and status monitoring. putting unused hardware components to sleep), auto configuration (e.g.

Example of ACPI tables of a Lenovo laptop.Īdvanced Configuration and Power Interface ( ACPI) is an open standard that operating systems can use to discover and configure computer hardware components, to perform power management (e.g.

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