What is the full form of ACPIO

Basics: Energy management with ACPI 3.0

ACPI operating states

Essentially, ACPI divides the power management structure into three different functional elements. Four global power management states with the designation G0 to G3 function as higher-level instances.

The G0 or S0 mode defines a fully active system. The user can access all system components in real time, provided they are not in a power-saving mode. In addition, the peripheral devices can change their power status dynamically.

The opposite of G0 is G3 status. This represents a system that is completely separated from the mains so that all components are de-energized.

ACPI refers to the G2 or S5 status as "soft-off mode", which is activated via software or a correspondingly configured power switch. The system only draws a minimum of electrical energy from the active 5-volt standby line of the power supply unit. In order to start the system, it must go through a full boot process.

In G1 sleep mode, large parts of the active elements of the operating system are stored on the hard disk or in memory. All components such as memory, chipset, keyboard or mouse that are necessary for a wake-up event continue to be supplied with power by the power supply unit.

Legacy mode has a special status. It is only active if no ACPI operating system is available due to the corresponding BIOS configuration. Thanks to special interrupt mechanisms and register entries, a system can nevertheless switch directly from the G3 or G2 operating state to the G0 operating state via legacy boot.

ACPI divides the global classification of the operating states G0 to G3 of a system into six further graduated so-called "sleeping states" S0 to S5. These include, for example, functions such as "Suspend to RAM" (S3) and "Suspend to Disk" (S4). In the frequently used S1 mode, the system sleeps, but can be activated quickly without any noticeable delay, as the system does not have to reinitialize the chipset and the CPU. In addition, connected components such as modems, IDE / SATA hard disks, PCI-Express components or optical drives can have four further optional and system-independent energy-saving modes.