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AIX Version 4.3 Kernel and Subsystems Technical Reference, Volume 1

d_unmap_page Kernel Service


Deallocates resources previously allocated on a d_unmap_page call.


#include <sys/dma.h>
void d_unmap_page (*handle, *busaddr)
struct d_handle *handle
uint *busaddr
Note: The following is the interface definition for d_unmap_page when the DMA_ADDRESS_64 and DMA_ENABLE_64 flags are set on the d_map_init call.
int d_unmap_page(*handle, 
struct d_handle *handle;
unsigned long long *busaddr;


handle Indicates the unique handle returned by the d_map_init kernel service.
busaddr Points to the busaddr field.


The d_unmap_page kernel service is a bus-specific utility routine determined by the d_map_init kernel service that deallocates resources previously allocated on a d_map_page call for a DMA master device.

The d_unmap_page service must be called after I/O completion involving the area mapped by the prior d_map_page call. Some device drivers might choose to leave pages mapped for a long-term mapping of certain memory buffers. In this case, the driver must call d_unmap_page when it no longer needs the long-term mapping.

Note: You can use the D_UNMAP_PAGE macro provided in the /usr/include/sys/dma.h file to code calls to the d_unmap_page kernel service. If not, you must ensure that the d_unmap_page function pointer is non-NULL before attempting the call. Not all platforms require the unmapping service.

Implementation Specifics

The d_unmap_page kernel service is part of the base device package of your platform.

Related Information

The d_map_init kernel service.

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