WDF_IO_QUEUE_CONFIG structure (wdfio.h)
[Applies to KMDF and UMDF]
The WDF_IO_QUEUE_CONFIG structure contains configuration information for a framework queue object.
Syntax
typedef struct _WDF_IO_QUEUE_CONFIG {
ULONG Size;
WDF_IO_QUEUE_DISPATCH_TYPE DispatchType;
WDF_TRI_STATE PowerManaged;
BOOLEAN AllowZeroLengthRequests;
BOOLEAN DefaultQueue;
PFN_WDF_IO_QUEUE_IO_DEFAULT EvtIoDefault;
PFN_WDF_IO_QUEUE_IO_READ EvtIoRead;
PFN_WDF_IO_QUEUE_IO_WRITE EvtIoWrite;
PFN_WDF_IO_QUEUE_IO_DEVICE_CONTROL EvtIoDeviceControl;
PFN_WDF_IO_QUEUE_IO_INTERNAL_DEVICE_CONTROL EvtIoInternalDeviceControl;
PFN_WDF_IO_QUEUE_IO_STOP EvtIoStop;
PFN_WDF_IO_QUEUE_IO_RESUME EvtIoResume;
PFN_WDF_IO_QUEUE_IO_CANCELED_ON_QUEUE EvtIoCanceledOnQueue;
union {
struct {
ULONG NumberOfPresentedRequests;
} Parallel;
} Settings;
WDFDRIVER Driver;
} WDF_IO_QUEUE_CONFIG, *PWDF_IO_QUEUE_CONFIG;
Members
Size
The length, in bytes, of this structure.
DispatchType
A WDF_IO_QUEUE_DISPATCH_TYPE enumerator that identifies the request dispatching type for the queue.
PowerManaged
A WDF_TRI_STATE-typed value that, if set to WdfTrue, indicates that the framework handles power management of the queue.
If set to WdfFalse, the driver must handle power management of the queue.
If set to WdfUseDefault, the framework handles power management for the queue unless the driver calls WdfFdoInitSetFilter.
Drivers above the power policy owner in the driver stack must not set the PowerManaged member to WdfTrue.
For more information about power-managed I/O queues, see Power Management for I/O Queues.
AllowZeroLengthRequests
A Boolean value that, if TRUE, indicates that the driver expects to receive read or write requests that have a buffer length of zero, so the framework delivers these requests to the driver. If FALSE, the framework does not deliver these requests to the driver; instead, it completes them with a completion status of STATUS_SUCCESS.
DefaultQueue
A Boolean value that, if TRUE, indicates that the queue will be the device's default I/O queue. If FALSE, the queue will not be the device's default queue.
EvtIoDefault
A pointer to the driver's queue-specific EvtIoDefault callback function, or NULL.
EvtIoRead
A pointer to the driver's queue-specific EvtIoRead callback function, or NULL.
EvtIoWrite
A pointer to the driver's queue-specific EvtIoWrite callback function, or NULL.
EvtIoDeviceControl
A pointer to the driver's queue-specific EvtIoDeviceControl callback function, or NULL.
EvtIoInternalDeviceControl
A pointer to the driver's queue-specific EvtIoInternalDeviceControl callback function, or NULL.
EvtIoStop
A pointer to the driver's queue-specific EvtIoStop callback function, or NULL.
EvtIoResume
A pointer to the driver's queue-specific EvtIoResume callback function, or NULL.
EvtIoCanceledOnQueue
A pointer to the driver's queue-specific EvtIoCanceledOnQueue callback function, or NULL.
Settings
Settings.Parallel
Settings.Parallel.NumberOfPresentedRequests
For the parallel dispatching method, the maximum number of I/O requests that the framework asynchronously delivers to the I/O queue's request handlers. For more information, see the following Remarks section. For the sequential and manual dispatching methods, this member must be zero. This member is available in version 1.9 and later versions of KMDF.
Driver
For internal use only. Set to NULL. This member is available in version 1.11 and later versions of KMDF.
Remarks
The driver must initialize the WDF_IO_QUEUE_CONFIG structure by calling WDF_IO_QUEUE_CONFIG_INIT or WDF_IO_QUEUE_CONFIG_INIT_DEFAULT_QUEUE.
The WDF_IO_QUEUE_CONFIG structure is used as an input parameter to WdfIoQueueCreate.
Beginning with version 1.9 of KMDF, drivers can use the NumberOfPresentedRequests member to specify the maximum number of I/O requests that the framework asynchronously delivers to a parallel I/O queue's request handlers. After the framework has delivered the specified number of I/O requests to the driver, it does not deliver more requests from the queue until the driver completes, cancels, or requeues at least one of the requests.
For parallel queues, WDF_IO_QUEUE_CONFIG_INIT and WDF_IO_QUEUE_CONFIG_INIT_DEFAULT_QUEUE set the NumberOfPresentedRequests member to its default value (-1), which indicates that the framework can deliver an unlimited number of I/O requests to the driver.
Requirements
| Requirement | Value |
|---|---|
| Minimum KMDF version | 1.0 |
| Minimum UMDF version | 2.0 |
| Header | wdfio.h (include Wdf.h) |