Manual page for ddi_iopb_alloc(9F)
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,
u_int length,
caddr_t *iopbp);
void ddi_iopb_free(caddr_t iopb);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
ARGUMENTS
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
ddi_iopb_alloc()
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.
ddi_iopb_free()
frees up memory allocated by
ddi_iopb_alloc().
RETURN VALUES
ddi_iopb_alloc()
returns:
- DDI_SUCCESS
-
Memory successfully allocated.
- DDI_FAILURE
-
Allocation failed.
CONTEXT
These functions can be called from user or interrupt context.
SEE ALSO
ddi_dma_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
NOTES
This function uses scarce system resources. Use it selectively.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
