NdisMWriteLogData function

NdisMWriteLogData transfers driver-supplied information into the log file for consumption and display by a driver-dedicated Win32 application.


NDIS_STATUS NdisMWriteLogData(
  NDIS_HANDLE LogHandle,
  PVOID       LogBuffer,
  UINT        LogBufferSize



Specifies the handle returned by NdisMCreateLog.


Pointer to a driver-allocated buffer containing the information to be written.


Specifies how many bytes of data to copy into the log file.

Return Value

NdisMWriteLogData can return one of the following:

Return code Description
The driver-supplied data at LogBuffer has been copied into the log file.
The given LogBufferSize is too large, that is, larger than the log file itself.


If the driver-dedicated application has an outstanding request for log file data, NdisMWriteLogData satisfies that request as soon as it has copied the driver-supplied information into the log file.

The miniport driver can supply a LogBuffer pointer to a location on the kernel stack if it is currently running at IRQL < DISPATCH_LEVEL. Otherwise, LogBuffer must access a buffer that the driver allocated from nonpaged pool.

The driver must release any spin lock it is holding before calling NdisMWriteLogData.

NdisMWriteLogData does not recognize boundaries between log records, nor does the Win32 function, DeviceIoControl, which applications can call with IOCTL_NDIS_GET_LOG_DATA to retrieve data written to an NDIS log file by an NDIS miniport driver. NdisMWriteLogData writes all miniport driver-supplied data at LogBuffer into the log file as a byte stream. DeviceIoControl reads the data from such a log as a byte stream, as well.

Consequently, an application reading an NDIS log must collect retrieved data into records. To aid such an application in collecting variable-length records, any miniport driver writing to such a log can insert a marker at the beginning of each record. Then, the application formatting the retrieved data can search for these markers to determine the start of each record.


Minimum supported client Supported for NDIS 6.0 and NDIS 5.1 drivers (see NdisMWriteLogData (NDIS 5.1)) in Windows Vista. Supported for NDIS 5.1 drivers (see NdisMWriteLogData (NDIS 5.1)) in Windows XP.
Target Platform Universal
Header ndis.h (include Ndis.h)
Library Ndis.lib
DDI compliance rules Irql_Miniport_Driver_Function

See Also

NdisAllocateFromNPagedLookasideList NdisAllocateMemoryWithTagPriority