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PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER union (ntddk.h)

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The PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER structure describes a PCI Express (PCIe) device capabilities register of a PCIe capability structure.

Syntax

typedef union _PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER {
  struct {
    ULONG MaxPayloadSizeSupported  :3;
    ULONG PhantomFunctionsSupported  :2;
    ULONG ExtendedTagSupported  :1;
    ULONG L0sAcceptableLatency  :3;
    ULONG L1AcceptableLatency  :3;
    ULONG Undefined  :3;
    ULONG RoleBasedErrorReporting  :1;
    ULONG Rsvd1  :2;
    ULONG CapturedSlotPowerLimit  :8;
    ULONG CapturedSlotPowerLimitScale  :2;
    ULONG Rsvd2  :4;
  };
  ULONG  AsULONG;
} PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER, *PPCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER;

Members

DUMMYSTRUCTNAME

DUMMYSTRUCTNAME.MaxPayloadSizeSupported

The maximum payload size that is supported by the device. Possible values are:

MaxPayload128Bytes

128 byte maximum payload size

MaxPayload256Bytes

256 byte maximum payload size

MaxPayload512Bytes

512 byte maximum payload size

MaxPayload1024Bytes

1024 byte maximum payload size

MaxPayload2048Bytes

2048 byte maximum payload size

MaxPayload4096Bytes

4096 byte maximum payload size

DUMMYSTRUCTNAME.PhantomFunctionsSupported

A value that indicates the support of unused function numbers (phantom functions) to extend the number of outstanding transactions that are allowed for the device. Possible values are:

0

No function number bits are used for phantom functions. The device can implement functions for all eight function numbers.

1

The most significant bit in the function number is used for phantom functions. The device can implement functions for function numbers 0 to 3.

2

The two most significant bits in the function number are used for phantom functions. The device can implement functions for function numbers 0 and 1.

3

All three bits in the function number are used for phantom functions. The device implements only a single function for function number 0.

DUMMYSTRUCTNAME.ExtendedTagSupported

A single bit that specifies the maximum supported size of the Tag field in a PCIe transaction descriptor when the device is a requester. If this bit is clear, a 5-bit Tag field is supported. If this bit is set, an 8-bit Tag field is supported.

DUMMYSTRUCTNAME.L0sAcceptableLatency

The maximum acceptable total latency that the device can withstand due to a transition from the L0s state to the L0 state. Possible values are:

L0s_Below64ns

64 nanoseconds

L0s_64ns_128ns

128 nanoseconds

L0s_128ns_256ns

256 nanoseconds

L0s_256ns_512ns

512 nanoseconds

L0s_512ns_1us

1 microsecond

L0s_1us_2us

2 microseconds

L0s_2us_4us

4 microseconds

L0s_Above4us

No limit

DUMMYSTRUCTNAME.L1AcceptableLatency

The maximum acceptable total latency that the device can withstand due to a transition from the L1 state to the L0 state. Possible values are:

L1_Below1us

1 microsecond

L1_1us_2us

2 microseconds

L1_2us_4us

4 microseconds

L1_4us_8us

8 microseconds

L1_8us_16us

16 microseconds

L1_16us_32us

32 microseconds

L1_32us_64us

64 microseconds

L1_Above64us

No limit

DUMMYSTRUCTNAME.Undefined

Reserved.

DUMMYSTRUCTNAME.RoleBasedErrorReporting

A single bit that indicates that the device implements role-based error reporting.

DUMMYSTRUCTNAME.Rsvd1

Reserved.

DUMMYSTRUCTNAME.CapturedSlotPowerLimit

The maximum amount of power that can be supplied by the slot. This value is used in combination with the value of the CapturedSlotPowerLimitScale member to compute the power in watts.

DUMMYSTRUCTNAME.CapturedSlotPowerLimitScale

The scale used for the value contained in the CapturedSlotPowerLimit member to compute the maximum power, in watts, that can be supplied by the slot. Possible values are:

0

Multiply the value in the CapturedSlotPowerLimit member by 1.0.

1

Multiply the value in the CapturedSlotPowerLimit member by 0.1.

2

Multiply the value in the CapturedSlotPowerLimit member by 0.01.

3

Multiply the value in the CapturedSlotPowerLimit member by 0.001.

DUMMYSTRUCTNAME.FunctionLevelResetCapability

DUMMYSTRUCTNAME.Rsvd2

Reserved.

AsULONG

A ULONG representation of the contents of the PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER structure.

Remarks

The PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER structure is available in Windows Server 2008 and later versions of Windows.

A PCI_EXPRESS_DEVICE_CAPABILITIES_REGISTER structure is contained in the PCI_EXPRESS_CAPABILITY structure.

Requirements

Requirement Value
Header ntddk.h (include Ntddk.h, Miniport.h)

See also

PCI_EXPRESS_CAPABILITY