[Applies to KMDF only]

A driver's EvtIoInternalDeviceControl event callback function processes an I/O request that contains an internal device I/O control code (IOCTL).



VOID EvtIoInternalDeviceControl(
  _In_ WDFQUEUE   Queue,
  _In_ WDFREQUEST Request,
  _In_ size_t     OutputBufferLength,
  _In_ size_t     InputBufferLength,
  _In_ ULONG      IoControlCode
{ ... }


Queue [in]

A handle to the framework queue object that is associated with the I/O request.

Request [in]

A handle to a framework request object.

OutputBufferLength [in]

The length, in bytes, of the request's output buffer, if an output buffer is available.

InputBufferLength [in]

The length, in bytes, of the request's input buffer, if an input buffer is available.

IoControlCode [in]

The driver-defined or system-defined IOCTL that is associated with the request.

Return value



A driver registers an EvtIoInternalDeviceControl callback function when it calls the WdfIoQueueCreate method. For more information about calling WdfIoQueueCreate, see Creating I/O Queues.

If a driver has registered an EvtIoInternalDeviceControl callback function for a device's I/O queue, the callback function receives every internal I/O control request (IRP_MJ_INTERNAL_DEVICE_CONTROL) from the queue. For more information, see Request Handlers.

The EvtIoInternalDeviceControl callback function must process each received I/O request in some manner. For more information, see Processing I/O Requests.

Drivers receive internal I/O control requests when another driver creates a request by calling either WdfIoTargetSendInternalIoctlSynchronously or WdfIoTargetFormatRequestForInternalIoctl.

The type of operation to be performed depends on the value of the IoControlCode parameter. You must determine the set of IoControlCode values that applications and other drivers can send to your driver. For more information about IOCTLs, see Using I/O Control Codes.

Most internal I/O control operations require an input buffer, an output buffer, or both. For information about how the driver can access a request's buffers, see Accessing Data Buffers in Framework-Based Drivers.

The techniques that your driver can use to access the request's input and output buffers (if they exist) depend on the TransferType field of the IOCTL. The value of the IOCTL's TransferType field can be METHOD_BUFFERED, METHOD_DIRECT_IN, METHOD_DIRECT_OUT, or METHOD_NEITHER. For more information about the TransferType field, see Defining I/O Control Codes.

The EvtIoInternalDeviceControl callback function can be called at IRQL <= DISPATCH_LEVEL, unless the ExecutionLevel member of the device or driver's WDF_OBJECT_ATTRIBUTES structure is set to WdfExecutionLevelPassive.

If the IRQL is PASSIVE_LEVEL, the framework calls the callback function within a critical region.

For more information about IRQL levels for request handlers, see Using Automatic Synchronization.

A driver's EvtIoInternalDeviceControl callback function should not call the following queue object methods:



To define an EvtIoInternalDeviceControl 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 EvtIoInternalDeviceControl callback function that is named MyIoInternalDeviceControl, use the EVT_WDF_IO_QUEUE_IO_INTERNAL_DEVICE_CONTROL type as shown in this code example:


Then, implement your callback function as follows:

 MyIoInternalDeviceControl (
    WDFQUEUE  Queue,
    WDFREQUEST  Request,
    size_t  OutputBufferLength,
    size_t  InputBufferLength,
    ULONG  IoControlCode

The EVT_WDF_IO_QUEUE_IO_INTERNAL_DEVICE_CONTROL function type is defined in the Wdfio.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_IO_QUEUE_IO_INTERNAL_DEVICE_CONTROL 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.


Target platform


Minimum KMDF version


Minimum UMDF version



Wdfio.h (include Wdf.h)


<= DISPATCH_LEVEL (see Remarks section)

See also




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