SVR5

dma_get_cb(D3)

dma_get_cb -- allocate a DMA command block

Synopsis

   #include <sys/types.h>
   #include <sys/dma.h>
   #include <sys/ddi.h>

   struct dma_cb *dma_get_cb(uchar_t mode);

Description

dma_get_cb allocates memory for a dma_cb(D4) DMA command block structure, zeroes it out, and returns a pointer to the structure.

Arguments

mode: Specifies whether the caller is willing to sleep waiting for memory.

Return values

dma_get_cb returns a pointer to the allocated DMA control block. If DMA_NOSLEEP is specified and memory for a dma_cb is not immediately available, dma_get_cb returns a NULL pointer.

Usage

If mode is set to DMA_SLEEP, the caller will sleep if necessary until the memory for a dma_cb is available. If mode is set to DMA_NOSLEEP, the caller will not sleep, but dma_get_cb will return NULL if memory for a dma_cb is not immediately available.

Context and synchronization

If mode is set to DMA_NOSLEEP, non-blockable, initialization, or interrupt context.

If mode is set to DMA_SLEEP, user context.

Hardware applicability

PC-AT compatible platforms with ISA, EISA, or MCA buses

Version applicability

ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp

Future directions

This interface is expected to be replaced or modified in a future release.

References

dma_free_cb(D3), dma_cb(D4)

``DMA'' in HDK Technical Reference