Content-type: text/html Man page of ddi_iopb_alloc

ddi_iopb_alloc

Section: Kernel Functions for Drivers (9F)
Updated: 04 Apr 2006
Index Return to Main Contents
 

NAME

ddi_iopb_alloc, ddi_iopb_free - allocate and free non-sequentially accessed memory  

SYNOPSIS

#include <sys/ddi.h>
#include <sys/sunddi.h>

int ddi_iopb_alloc(dev_info_t *dip, ddi_dma_lim_t *limits, uint_t length, caddr_t *iopbp);

void ddi_iopb_free(caddr_t iopb);  

INTERFACE LEVEL

These interfaces are obsolete. Use ddi_dma_mem_alloc(9F) instead of ddi_iopb_alloc(). Use ddi_dma_mem_free(9F) instead of ddi_iopb_free().  

PARAMETERS

 

ddi_iopb_alloc()

dip A pointer to the device's dev_info structure.

limits A pointer to a DMA limits structure for this device (see ddi_dma_lim_sparc(9S) or ddi_dma_lim_x86(9S)). If this pointer is NULL, a default set of DMA limits is assumed.

length The length in bytes of the desired allocation.

iopbp A pointer to a caddr_t. On a successful return, *iopbp points to the allocated storage.

 

ddi_iopb_free()

iopb The iopb returned from a successful call to ddi_iopb_alloc().

 

DESCRIPTION

The ddi_iopb_alloc() function allocates memory for DMA transfers and should be used if the device accesses memory in a non-sequential fashion, or if synchronization steps using ddi_dma_sync(9F) should be as lightweight as possible, due to frequent use on small objects. This type of access is commonly known as consistent access. The allocation will obey the alignment and padding constraints as specified in the limits argument and other limits imposed by the system.

Note that you still must use DMA resource allocation functions (see ddi_dma_setup(9F)) to establish DMA resources for the memory allocated using ddi_iopb_alloc().

In order to make the view of a memory object shared between a CPU and a DMA device consistent, explicit synchronization steps using ddi_dma_sync(9F) or ddi_dma_free(9F) are still required. The DMA resources will be allocated so that these synchronization steps are as efficient as possible.

The ddi_iopb_free() function frees up memory allocated by ddi_iopb_alloc().  

RETURN VALUES

The ddi_iopb_alloc() function returns:

DDI_SUCCESS Memory successfully allocated.

DDI_FAILURE Allocation failed.

 

CONTEXT

These functions can be called from user, interrupt, or kernel context.  

ATTRIBUTES

See attributes(5) for a description of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Stability LevelObsolete

 

SEE ALSO

attributes(5), ddi_dma_free(9F), ddi_dma_mem_alloc(9F), ddi_dma_mem_free(9F), ddi_dma_setup(9F), ddi_dma_sync(9F), ddi_mem_alloc(9F), ddi_dma_lim_sparc(9S), ddi_dma_lim_x86(9S), ddi_dma_req(9S)

Writing Device Drivers  

NOTES

This function uses scarce system resources. Use it selectively.


 

Index

NAME
SYNOPSIS
INTERFACE LEVEL
PARAMETERS
ddi_iopb_alloc()
ddi_iopb_free()
DESCRIPTION
RETURN VALUES
CONTEXT
ATTRIBUTES
SEE ALSO
NOTES

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Time: 02:39:42 GMT, October 02, 2010