Acpi X86 Pc3/17/2021
Standard Intel -based PCs have a fixed function interface defined by Intel, 38 which provides a set of core functionality that reduces an ACPI-compliant systems need for full driver stacks for providing basic functionality during boot time or in the case of major system failure.Please help improve this article by adding citations to reliable sources.Find sources: Advanced Configuration and Power Interface news newspapers books scholar JSTOR ( July 2010 ) ( Learn how and when to remove this template message ).
First released in December 1996, ACPI aims to replace Advanced Power Management (APM), the MultiProcessor Specification, and the Plug and Play BIOS (PnP) Specification. ACPI brings the 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. The specification is central to the Operating System-directed configuration and Power Management ( OSPM ) system, an implementation for ACPI which removes device management responsibilities from legacy firmware interfaces via a UI. ACPI defines a hardware abstraction interface between the system firmware ( BIOS or UEFI ) and the operating systems 3 4. ACPI then executes the desired operations written in ACPI Machine Language (such as the initialization of hardware components) using an embedded minimal virtual machine. 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. Unlike its predecessors, such as the APM or PnP BIOS, the ACPI implements little of its functionality in the ACPI BIOS code, whose main role is to load the ACPI tables in system memory. Instead, most 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. To make use of these tables, the operating system must have an interpreter for the AML bytecode. A reference AML interpreter implementation is provided by the ACPI Component Architecture (ACPICA). At the BIOS development time, AML bytecode is compiled from the ASL (ACPI Source Language) code. ![]() In November 2003, Linus Torvalds author of the Linux kernel described ACPI as a complete design disaster in every way. Acpi X86 Pc Software Developers LikeIn 2001, other senior Linux software developers like Alan Cox expressed concerns about the requirements that bytecode from an external source must be run by the kernel with full privileges, as well as the overall complexity of the ACPI specification. ![]() It was not until August 2000 that ACPI received 64-bit address support as well as support for multiprocessor workstations and servers with revision 2.0. The OSPM implementation must expose an ACPI-compatible environment to device drivers, which exposes certain system, device and processor states. Awaymode is a subset of S0, where monitor is off but background tasks are running. Devices that do not indicate they must remain on may be powered off. ![]() The power cord can be removed and the system is safe for disassembly (typically, only the real-time clock continues to run using its own small battery). In this state, the hardware and power are not managed via ACPI, effectively disabling ACPI. All ACPI-conformant processors must support this power state. Some processors, such as the Pentium 4, also support an Enhanced C1 state ( C1E or Enhanced Halt State) for lower power consumption. Some processors have variations on the C3 state (Deep Sleep, Deeper Sleep, etc.) that differ in how long it takes to wake the processor. For example, Intel s Haswell platform has states up to C10, where it distinguishes core states and package states. Though, P0 is always the highest-performance state; with P1 to P n being successively lower-performance states, up to an implementation-specific limit of n no greater than 16.
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