PFREE_COMMON_BUFFER callback function (wdm.h)

The FreeCommonBuffer routine frees a common buffer allocated by AllocateCommonBuffer, along with all resources the buffer uses.

Syntax

PFREE_COMMON_BUFFER PfreeCommonBuffer;

void PfreeCommonBuffer(
  [in] PDMA_ADAPTER DmaAdapter,
  [in] ULONG Length,
  [in] PHYSICAL_ADDRESS LogicalAddress,
  [in] PVOID VirtualAddress,
  [in] BOOLEAN CacheEnabled
)
{...}

Parameters

[in] DmaAdapter

Pointer to the DMA_ADAPTER structure returned by IoGetDmaAdapter that represents the bus-master adapter or DMA controller.

[in] Length

Specifies the number of bytes to deallocate.

[in] LogicalAddress

Specifies the logical address of the allocated memory range.

[in] VirtualAddress

Pointer to the corresponding virtual address of the allocated memory range.

[in] CacheEnabled

Indicates whether the allocated memory is cached.

Return value

None

Remarks

FreeCommonBuffer is not a system routine that can be called directly by name. This routine is callable only by pointer from the address returned in a DMA_OPERATIONS structure. Drivers obtain the address of this routine by calling IoGetDmaAdapter.

To release a common buffer, a driver calls FreeCommonBuffer to unmap both its logical and virtual addresses. The parameters passed to FreeCommonBuffer must match exactly those passed to and returned from AllocateCommonBuffer. A driver cannot free part of an allocated common buffer.

Requirements

See also

AllocateCommonBuffer

DMA_ADAPTER

DMA_OPERATIONS

IoGetDmaAdapter