ACPI BIOS Specification
System States
The S99K 2U hardware supports these ACPI states as followings. The S99K 2U could wake up from S0, S1 and S4.
G0, System in working mode
While the system is in the S0 state, it is in the system working state. The behavior of this state is defined as:
The processors are in the C0, C1, C2, or C3 states. The processor complex context is maintained and instructions are
executed as defined by any of these processor states.
Dynamic RAM context is maintained and is read/write by the processors.
Devices states are individually managed by the operating software and can be in any device state (D0, D1, D2 or D3).
Power Resources are in a state compatible with the current device states.
Transition into the S0 state from some system sleeping state is automatic, and by virtue that instructions are being executed
the OS assumes the system to be in the S0 state.
G1, System in Suspend to Memory
While the system is in this state, it is in the system S4 sleeping state. The state is logically lower than the S1 state and is
assumed to conserve more power. The behavior of this state is defined as follows:
The processors are not executing instructions. The processor complex context is not maintained.
Dynamic RAM context is maintained.
Power Resources are in a state compatible with the system S4 state. All Power Resources that supply a System Level
reference of S0 or S1 are in the OFF state.
Device states are compatible with the current Power Resource states. Only devices that solely reference Power
Resource that are in the On state for a given device state can be in that device state.
Devices that are enabled to wake the system and that can do so from their current device state can initiate a hardware
event that transitions the system state to S0.
Resume events are: Power button.
G1, System in Suspend to Disk mode (S4 is done by OS)
While the system is in this state, it is in the system S4 sleeping state. The state is logically lower than the S1 state and is
assumed to conserve more power. The behavior of this state is defined as follows:
The processors are not executing instructions. The processor complex context is not maintained.
Dynamic RAM context is not maintained.
Power Resources are in a state compatible with the system S4 state. All Power Resources that supply a System Level
reference of S0 or S1 are in the OFF state.
Device states are compatible with the current Power Resource states. In other words, all devices are in the D3 state
when the system state is S4.
Devices that are enabled to wake the system and that can do so from their D3 device state can initiate a hardware event
which transitions the system state to S0. This transition causes the processor to begin execution at its boot location.
Resume events are: Power button.
Chapter 3 — BIOS
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