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WDF_DEVICE_IO_TYPE enumeration (wdfdevice.h)

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[Applies to KMDF and UMDF]

The WDF_DEVICE_IO_TYPE enumeration is used to specify a method for accessing data buffers.

Syntax

typedef enum _WDF_DEVICE_IO_TYPE {
  WdfDeviceIoUndefined = 0,
  WdfDeviceIoNeither,
  WdfDeviceIoBuffered,
  WdfDeviceIoDirect,
  WdfDeviceIoBufferedOrDirect = 4,
  WdfDeviceIoMaximum
} WDF_DEVICE_IO_TYPE, *PWDF_DEVICE_IO_TYPE;

Constants

 
WdfDeviceIoUndefined
Value: 0
Reserved for system use.
WdfDeviceIoNeither
UMDF This value is not used by UMDF drivers. A UMDF driver can access device I/O control requests that specify the METHOD_NEITHER buffer access method by setting the UmdfMethodNeitherAction INF directive and using WdfDeviceIoBuffered or WdfDeviceIoDirect. For more information, see Specifying WDF Directives in INF Files.

KMDF Neither buffered nor direct I/O will be used to access data buffers.
WdfDeviceIoBuffered
Buffered I/O will be used to access data buffers.
WdfDeviceIoDirect
Direct I/O will be used to access data buffers.
WdfDeviceIoBufferedOrDirect
Value: 4
This value is not used by KMDF drivers.

UMDF Buffered I/O or direct I/O will be used to access data buffers.
WdfDeviceIoMaximum

Remarks

The WDF_DEVICE_IO_TYPE enumeration is used to specify buffer access method types in the WDF_IO_TYPE_CONFIG structure.

The WDF_IO_TYPE_CONFIG structure is used as input to WdfDeviceInitSetIoTypeEx and WdfDeviceInitSetIoType.

Requirements

Requirement Value
Minimum KMDF version 1.0
Minimum UMDF version 2.0
Header wdfdevice.h (include Wdf.h)

See also

WDF_IO_TYPE_CONFIG

WdfDeviceInitSetIoType

WdfDeviceInitSetIoTypeEx