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PCI_EXPRESS_LINK_CAPABILITIES_REGISTER union (miniport.h)

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The PCI_EXPRESS_LINK_CAPABILITIES_REGISTER union describes a PCI Express (PCIe) link capabilities register of a PCIe capability structure.

Syntax

typedef union _PCI_EXPRESS_LINK_CAPABILITIES_REGISTER {
  struct {
    ULONG MaximumLinkSpeed : 4;
    ULONG MaximumLinkWidth : 6;
    ULONG ActiveStatePMSupport : 2;
    ULONG L0sExitLatency : 3;
    ULONG L1ExitLatency : 3;
    ULONG ClockPowerManagement : 1;
    ULONG SurpriseDownErrorReportingCapable : 1;
    ULONG DataLinkLayerActiveReportingCapable : 1;
    ULONG LinkBandwidthNotificationCapability : 1;
    ULONG AspmOptionalityCompliance : 1;
    ULONG Rsvd : 1;
    ULONG PortNumber : 8;
  } DUMMYSTRUCTNAME;
  ULONG  AsULONG;
} PCI_EXPRESS_LINK_CAPABILITIES_REGISTER, *PPCI_EXPRESS_LINK_CAPABILITIES_REGISTER;

Members

DUMMYSTRUCTNAME

The DUMMYSTRUCTNAME structure.

DUMMYSTRUCTNAME.MaximumLinkSpeed

The maximum link speed of the PCIe link. The only valid value is:

1
2.5 gigabits per second

All other values are reserved.

DUMMYSTRUCTNAME.MaximumLinkWidth

The maximum link width (number of lanes) implemented by the component. Possible values are:

1
x1 (1 lane)

2
x2 (2 lanes)

4
x4 (4 lanes)

8
x8 (8 lanes)

12
x12 (12 lanes)

16
x16 (16 lanes)

32
x32 (32 lanes)

All other values are reserved.

DUMMYSTRUCTNAME.ActiveStatePMSupport

The level of active state power management supported on the PCIe link. Possible values are:

L0sEntrySupport
L0s is supported.

L0sAndL1EntrySupport
L0s and L1 are supported.

All other values are reserved.

DUMMYSTRUCTNAME.L0sExitLatency

The L0s exit latency for the PCIe link. This value indicates the length of time this port requires to complete a transition from L0s to L0.

L0s_Below64ns
Less than 64 nanoseconds

L0s_64ns_128ns
64 nanoseconds to 128 nanoseconds

L0s_128ns_256ns
128 nanoseconds to 256 nanoseconds

L0s_256ns_512ns
256 nanoseconds to 512 nanoseconds

L0s_512ns_1us
512 nanoseconds to 1 microsecond

L0s_1us_2us
1 microsecond to 2 microseconds

L0s_2us_4us
2 microseconds to 4 microseconds

L0s_Above4us
More than 4 microseconds

DUMMYSTRUCTNAME.L1ExitLatency

The L1 exit latency for the PCIe link. This value indicates the length of time this port requires to complete a transition from L1 to L0.

L1_Below1us
Less than 1 microsecond

L1_1us_2us
1 microsecond to 2 microseconds

L1_2us_4us
2 microseconds to 4 microseconds

L1_4us_8us
4 microseconds to 8 microseconds

L1_8us_16us
8 microseconds to 16 microseconds

L1_16us_32us
16 microseconds to 32 microseconds

L1_32us_64us
32 microseconds to 64 microseconds

L1_Above64us
More than 64 microseconds

This value is ignored if the ActiveStatePMSupport member is not set to L0sAndL1EntrySupport.

DUMMYSTRUCTNAME.ClockPowerManagement

A single bit that indicates that the component supports clock power management.

DUMMYSTRUCTNAME.SurpriseDownErrorReportingCapable

A single bit that indicates that the component supports the optional capability of detecting and reporting a surprise-down error condition. This bit only applies to downstream ports.

DUMMYSTRUCTNAME.DataLinkLayerActiveReportingCapable

A single bit that indicates that the component supports the optional capability of reporting the data link active state of the data link control and management state machine. This bit only applies to downstream ports. Hot-plug capable downstream ports must support this capability.

DUMMYSTRUCTNAME.LinkBandwidthNotificationCapability

Defines the ULONG member LinkBandwidthNotificationCapability.

DUMMYSTRUCTNAME.AspmOptionalityCompliance

Defines the ULONG member AspmOptionalityCompliance.

DUMMYSTRUCTNAME.Rsvd

Reserved.

DUMMYSTRUCTNAME.PortNumber

The PCIe port number for the PCIe link.

AsULONG

A ULONG representation of the contents of the PCI_EXPRESS_LINK_CAPABILITIES_REGISTER structure.

Remarks

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

A PCI_EXPRESS_LINK_CAPABILITIES_REGISTER structure is contained in the PCI_EXPRESS_CAPABILITY structure.

Requirements

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

See also

PCI_EXPRESS_CAPABILITY