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EvtDeviceUsageNotification function

[Applies to KMDF and UMDF]

A driver's EvtDeviceUsageNotification event callback function informs the driver when a device is being used for special files.



VOID EvtDeviceUsageNotification(
  _In_  WDFDEVICE Device,
  _In_  WDF_SPECIAL_FILE_TYPE NotificationType,
  _In_  BOOLEAN IsInNotificationPath
{ ... }


Device [in]

A handle to a framework device object.

NotificationType [in]

A WDF_SPECIAL_FILE_TYPE-typed value that identifies the type of special file that the system is storing on the specified device.

IsInNotificationPath [in]

A Boolean value which, if TRUE, indicates that the system has starting using the special file and, if FALSE, indicate that the system as finished using the special file.

Return value



To register an EvtDeviceUsageNotification callback function, a driver must call WdfDeviceInitSetPnpPowerEventCallbacks.

Your driver must provide an EvtDeviceUsageNotification callback function only if must provide driver-specific handling of special files.

For more information about special files, see Supporting Special Files.


To define an EvtDeviceUsageNotification callback function, you must first provide a function declaration that identifies the type of callback function you’re defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it’s a requirement for writing drivers for the Windows operating system.

For example, to define an EvtDeviceUsageNotification callback function that is named MyDeviceUsageNotification, use the EVT_WDF_DEVICE_USAGE_NOTIFICATION type as shown in this code example:


Then, implement your callback function as follows:

 MyDeviceUsageNotification (
    WDFDEVICE  Device,
    WDF_SPECIAL_FILE_TYPE NotificationType,
    BOOLEAN  IsInNotificationPath

The EVT_WDF_DEVICE_USAGE_NOTIFICATION function type is defined in the Wdfdevice.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the EVT_WDF_DEVICE_USAGE_NOTIFICATION function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.


Minimum KMDF version


Minimum UMDF version



Wdfdevice.h (include Wdf.h)





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