WdfCommonBufferCreateWithConfig function

[Applies to KMDF only]

The WdfCommonBufferCreateWithConfig method creates a memory buffer that both the driver and a direct memory access (DMA) device can access simultaneously, and the method also specifies buffer configuration information.

Syntax

NTSTATUS WdfCommonBufferCreateWithConfig(
  WDFDMAENABLER             DmaEnabler,
  size_t                    Length,
  PWDF_COMMON_BUFFER_CONFIG Config,
  PWDF_OBJECT_ATTRIBUTES    Attributes,
  WDFCOMMONBUFFER           *CommonBuffer
);

Parameters

DmaEnabler

A handle to a DMA enabler object that the driver obtained by a previous call to WdfDmaEnablerCreate.

Length

The desired size, in bytes, of the new buffer.

Config

A pointer to a WDF_COMMON_BUFFER_CONFIG structure that contains configuration information about the buffer.

Attributes

A pointer to a WDF_OBJECT_ATTRIBUTES structure that specifies object attributes for the common buffer object. (The structure's ParentObject member must be NULL.) This parameter is optional and can be WDF_NO_OBJECT_ATTRIBUTES.

CommonBuffer

A pointer to a WDFCOMMONBUFFER-typed variable that receives a handle to a common buffer object.

Return Value

WdfCommonBufferCreateWithConfig returns STATUS_SUCCESS if the operation succeeds. Otherwise, this method might return one of the following values:

Return code Description
STATUS_INVALID_PARAMETER
The driver supplied an invalid parameter.
STATUS_INSUFFICIENT_RESOURCES
The framework could not allocate a common buffer object, or the system could not allocate a buffer.
 

A bug check occurs if the driver supplies an invalid object handle.

Remarks

The WdfCommonBufferCreateWithConfig method allocates memory and maps it so that both the driver and a device can access it simultaneously for DMA operations.

Additionally, WdfCommonBufferCreateWithConfig enables your driver to specify a buffer alignment requirement for the buffer. The buffer alignment requirement overrides the buffer alignment requirement that the driver specified when it called WdfDeviceSetAlignmentRequirement. Your driver can use WdfCommonBufferCreateWithConfig, instead of WdfCommonBufferCreate, if you want the driver to create a buffer that has a different alignment requirement than the one that WdfDeviceSetAlignmentRequirement specified.

After your driver calls WdfCommonBufferCreateWithConfig, the driver must:

A driver typically calls WdfCommonBufferCreateWithConfig from within its EvtDriverDeviceAdd callback function.

The operating system determines whether to enable cached memory in the common buffer that is to be allocated. That decision is based on the processor architecture and device bus.

On computers with x86-based, x64-based, and Itanium-based processors, cached memory is enabled. On computers with ARM or ARM 64-based processors, the operating system does not automatically enable cached memory for all devices. The system relies on the ACPI_CCA method for each device to determine whether the device is cache-coherent.

For more information about common buffers, see Using Common Buffers

Examples

The following code example initializes a WDF_COMMON_BUFFER_CONFIG structure and then creates a 10-byte buffer that is aligned on a 32-byte boundary.

WDF_COMMON_BUFFER_CONFIG  commonBufConfig;
WDFCOMMONBUFFER  commonBuffer;

WDF_COMMON_BUFFER_CONFIG_INIT( &commonBufConfig, FILE_32_BYTE_ALIGNMENT );

status = WdfCommonBufferCreateWithConfig( DmaEnabler, 10, &commonBufConfig, WDF_NO_OBJECT_ATTRIBUTES, &commonBuffer ); if (!NT_SUCCESS (status)) { return status; }

Requirements

   
Target Platform Universal
Minimum KMDF version 1.1
Header wdfcommonbuffer.h (include WdfCommonBuffer.h)
Library Wdf01000.sys (see Framework Library Versioning.)
IRQL PASSIVE_LEVEL
DDI compliance rules DriverCreate, KmdfIrql, KmdfIrql2

See Also

EvtDriverDeviceAdd

WDF_COMMON_BUFFER_CONFIG

WDF_OBJECT_ATTRIBUTES

WdfCommonBufferCreate

WdfCommonBufferGetAlignedLogicalAddress

WdfCommonBufferGetAlignedVirtualAddress

WdfDeviceSetAlignmentRequirement

WdfDmaEnablerCreate