The Advanced Configuration and Power Interface (ACPI) is a standard for configuring and managing hardware devices in a computer system, with the goal of enabling power management features such as hibernation, sleep, and CPU throttling. ACPI is designed to work with the BIOS and the operating system to provide a consistent interface for managing hardware resources and power consumption.
In Linux, ACPI support is provided by the kernel through the ACPI subsystem, which provides a set of interfaces and services for handling ACPI-related events and requests. The ACPI subsystem is responsible for detecting ACPI hardware and loading the appropriate drivers, and for handling ACPI events such as power button presses and thermal events.
ACPI also provides a set of tables that describe the configuration and capabilities of hardware devices, such as the system BIOS and the CPU. These tables are used by the kernel and the operating system to determine the best way to manage power consumption and hardware resources.
One of the key features of ACPI in Linux is the ability to control the CPU frequency and voltage in order to reduce power consumption. This can be done using the cpufreq subsystem, which provides a set of interfaces and policies for adjusting the CPU frequency and voltage based on workload and other factors.
Another important feature of ACPI is the ability to manage system-wide power consumption, through features such as suspend-to-RAM and hibernation. These features allow the system to enter low-power states when idle, while preserving the current state of the system for later use.
Overall, ACPI plays a crucial role in enabling power management features in Linux, and is an important tool for reducing power consumption and extending battery life in portable devices.