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| Kernel Functions for Drivers | scsi_alloc_consistent_buf(9F) |
| | scsi_alloc_consistent_buf - allocate
an I/O buffer for SCSI DMA |
SYNOPSIS
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#include <sys/scsi/scsi.h>
struct buf *scsi_alloc_consistent_buf(structscsi_address*ap, struct buf *bp, size_t datalen, uint_t bflags, int (*callback, caddr_t),caddr_t arg); |
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Solaris DDI specific (Solaris DDI).
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ap
- Pointer to the scsi_address(9S) structure.
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bp
- Pointer
to the buf(9S)
structure.
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datalen
- Number of bytes for the data buffer.
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bflags
- Flags setting for the allocated buffer header. This should either be
B_READ or B_WRITE.
-
callback
- A pointer to a callback function, NULL_FUNC or SLEEP_FUNC.
-
arg
- The
callback function argument.
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scsi_alloc_consistent_buf() allocates a buffer
header and the associated data buffer for direct memory access (DMA) transfer.
This buffer is allocated from the iobp space, which is
considered consistent memory. For more details, see ddi_dma_mem_alloc(9F) and ddi_dma_sync(9F).
For buffers allocated via scsi_alloc_consistent_buf(),
and marked with the PKT_CONSISTENT
flag via scsi_init_pkt(9F),
the HBA driver must ensure that the data transfer for the command is correctly
synchronized before the target driver's command completion callback is performed.
If bp is NULL,
a new buffer header will be allocated using getrbuf(9F).
In addition, if datalen is non-zero, a new buffer
will be allocated using ddi_dma_mem_alloc(9F).
callback indicates what the allocator routines
should do when direct memory access (DMA) resources
are not available; the valid values are:
-
NULL_FUNC
- Do not
wait for resources. Return a NULL pointer.
-
SLEEP_FUNC
- Wait indefinitely for resources.
- Other Values
-
callback points to a function that is called when resources may become
available. callback must return either 0 (indicating that it attempted to allocate resources but
failed to do so), in which case it is put back on a list to be called again
later, or 1 indicating either success in allocating
resources or indicating that it no longer cares for a retry. The last argument arg is supplied to the callback function
when it is invoked.
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scsi_alloc_consistent_buf() returns a pointer to
a buf(9S) structure
on success. It returns NULL if resources are
not available even if waitfunc was not SLEEP_FUNC.
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If callback is SLEEP_FUNC,
then this routine may be called only from user-level code. Otherwise, it
may be called from either user or interrupt level. The callback function may not block or call routines that block.
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| | Example 1. Allocate a request sense packet with consistent
DMA resources attached.
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bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
SENSE_LENGTH, B_READ, SLEEP_FUNC, NULL);
rqpkt = scsi_init_pkt(&devp->sd_address,
NULL, bp, CDB_GROUP0, 1, 0,
PKT_CONSISTENT, SLEEP_FUNC, NULL);
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Example 2. Allocate an inquiry packet with consistent
DMA resources attached.
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bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
SUN_INQSIZE, B_READ, canwait, NULL);
if (bp) {
pkt = scsi_init_pkt(&devp->sd_address, NULL, bp,
CDB_GROUP0, 1, PP_LEN, PKT_CONSISTENT,
canwait, NULL);
}
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