OID_TIMESTAMP_GET_CROSSTIMESTAMP

An overlying driver issues an object identifier (OID) query request of OID_TIMESTAMP_GET_CROSSTIMESTAMP to obtain a cross timestamp from the NIC hardware. A cross timestamp is the set of a NIC hardware timestamp and system timestamp(s) obtained very close to each other. Precision Time Protocol (PTP) version 2 applications use the information provided in this OID to establish a relation between the NIC’s hardware clock and a system clock.

The miniport driver must support this OID if it sets the CrossTimestamp field to TRUE in the NDIS_TIMESTAMP_CAPABILITIES structure as part of the current configuration. For more details on reporting the current configuration, see the NDIS_STATUS_TIMESTAMP_CURRENT_CONFIG status indication. If the cross timestamping ability is disabled, then the OID should be completed with an appropriate error code (for example, NDIS_STATUS_NOT_SUPPORTED).

The RequestType member of the NDIS_OID_REQUEST structure will be NdisRequestQueryInformation.

When a miniport driver receives the OID request of OID_TIMESTAMP_GET_CROSSTIMESTAMP, the driver completes the OID by filling the InformationBuffer in the QUERY_INFORMATION with an NDIS_HARDWARE_CROSSTIMESTAMP structure. The Type field in the Header field of the NDIS_HARDWARE_CROSSTIMESTAMP structure should be set to NDIS_OBJECT_TYPE_DEFAULT and the Revision field to NDIS_HARDWARE_CROSSTIMESTAMP_REVISION_1. The driver should fill the SystemTimestamp1, HardwareClockTimestamp and SystemTimestamp2 fields with following timestamps taken as close to each other as possible and in the following order:

1. SystemTimestamp1: Performance counter value (QPC) obtained by calling KeQueryPerformanceCounter.

2. HardwareClockTimestamp: The NIC hardware clock’s current value. This should be the raw hardware clock value of the NIC.

3. SystemTimestamp2: Another performance counter value (QPC) obtained by calling KeQueryPerformanceCounter.

Here's an example of how a miniport driver handles OID_TIMESTAMP_GET_CROSSTIMESTAMP:

{
. . .
    NDIS_HARDWARE_CROSSTIMESTAMP crossTimestamp;
    LARGE_INTEGER timeStamp;

    RtlZeroMemory(&crossTimestamp, sizeof(crossTimestamp));

    timeStamp = KeQueryPerformanceCounter(NULL);
    crossTimestamp.SystemTimestamp1 = timeStamp.QuadPart;
    crossTimestamp.HardwareClockTimestamp = FunctionToRetrieveHardwareTimestampFromNetworkCard();
    timeStamp = KeQueryPerformanceCounter(NULL);
    crossTimestamp.SystemTimestamp2 = timeStamp.QuadPart;
    crossTimestamp.Header.Type = NDIS_OBJECT_TYPE_DEFAULT;
    crossTimestamp.Header.Size = NDIS_SIZEOF_HARDWARE_CROSSTIMESTAMP_REVISION_1;
    crossTimestamp.Header.Revision = NDIS_HARDWARE_CROSSTIMESTAMP_REVISION_1;

// Complete the OID by filling the query information buffer with the crossTimestamp
}

The Flags field in the NDIS_HARDWARE_CROSSTIMESTAMP structure is reserved for future use. The miniport driver must not change its value.

The miniport driver and hardware are free to optimize the collection of these timestamps depending on any advanced hardware capabilities. However, the SystemTimestamp1 and SystemTimestamp2 values returned on OID completion must accurately correspond to the performance counter (QPC) value at the time of capture. The HardwareClockTimestamp must correspond to the NIC’s hardware clock value at the point of capture. If a particular implementation can more accurately determine two timestamps rather than three (for example, one system timestamp and the corresponding NIC hardware clock timestamp), then it should set the SystemTimestamp2 field to the same value as SystemTimestamp1.

The miniport driver should not set the SystemTimestamp1, HardwareClockTimestamp, or SystemTimestamp2 values to zero.

Return Status Codes

The miniport driver returns one of the following status codes for the OID query request of OID_TIMESTAMP_GET_CROSSTIMESTAMP.

Requirements

See also

NDIS_STATUS_TIMESTAMP_CAPABILITY

OID_TIMESTAMP_CURRENT_CONFIG

OID_TIMESTAMP_CAPABILITY

NDIS_OID_REQUEST