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PEP_PPM_CST_STATE structure (pep_x.h)

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The PEP_PPM_CST_STATE structure specifies the properties of a C state (ACPI processor power state).

Syntax

typedef struct _PEP_PPM_CST_STATE {
  UCHAR            Type;
  USHORT           Latency;
  ULONG            Power;
  UCHAR            AddressSpaceId;
  UCHAR            BitWidth;
  UCHAR            BitOffset;
  UCHAR            AccessSize;
  PHYSICAL_ADDRESS Address;
} PEP_PPM_CST_STATE, *PPEP_PPM_CST_STATE;

Members

Type

The C-state type (0 = C0, 1 = C1, 2 = C2, and so on).

Latency

The worst-case latency, in microseconds, to enter and exit this C state. There are no restrictions on latency size.

Power

The average power consumption, in milliwatts, of the processor when in this C state.

AddressSpaceId

The register address space ID (_ASI) for this C state. This member specifies the address space in which the register for this C state is located. The following IDs are defined for this member.

ID Meaning
0x00 System memory space
0x01 System I/O space
0x02 PCI configuration space
0x03 Embedded controller
0x04 SMBus address
0x0A Platform communications channel (PCC)
0x7F Functional fixed hardware

BitWidth

The register bit width (_RBW) for this C state. This member specifies the width, in bits, of the register for this C state.

BitOffset

The register bit offset (_RBO) for this C state. This member specifies the offset, in bits, from the register address specified in the Address member to the start of the register for this C state.

AccessSize

The register access size (_ASZ) code for this C state. This member specifies the number of bytes to read during an access of the register for this C state. Valid access size codes are shown in the following table.

Access size code Meaning
0 Undefined
1 BYTE (1 byte)
2 WORD (2 bytes)
3 DWORD (4 bytes)
4 QWORD (8 bytes)

Address

The register address (_ADR) for this C state.

Remarks

This structure is used in conjunction with the PEP_NOTIFY_PPM_CST_STATES notification. The IdleStates member of the PEP_PPM_CST_STATES structure is a pointer to an array of PEP_PPM_CST_STATE structures. The Type member in each element of the array should equal the array index of this member.

The values in the PEP_PPM_CST_STATE structure are obtained from the parameters that are specified for this C state in the _CST object in the ACPI namespace for the processor.

Requirements

Requirement Value
Minimum supported client Supported starting with Windows 10.
Header pep_x.h (include Pep_x.h)

See also

PEP_NOTIFY_PPM_CST_STATES

PEP_PPM_CST_STATES