ddi_iopb_alloc(9F) manual page
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ddi_iopb_alloc, ddi_iopb_free - allocate and free non-sequentially accessed
memory
#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);
Solaris
DDI specific (Solaris DDI).
- 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.
- iopb
- The
iopb returned from a successful call to ddi_iopb_alloc().
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().
ddi_iopb_alloc() returns:
- DDI_SUCCESS
- Memory successfully
allocated.
- DDI_FAILURE
- Allocation failed.
These functions can be
called from user or interrupt context.
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)
This function uses scarce system resources. Use it
selectively.
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