struct scsi_pkt *scsi_pktalloc(struct scsi_address*ap, intcmdlen, intstatuslen, int(*callback )(void));
struct scsi_pkt *scsi_resalloc(struct scsi_address*ap, intcmdlen, intstatuslen, opaque_tdmatoken, int(*callback )(void));
The scsi_pktalloc(), scsi_pktfree(), scsi_resalloc(), and scsi_resfree() functions are obsolete. The scsi_pktalloc() and scsi_resalloc() functions have been replaced by scsi_init_pkt(9F). The scsi_pktfree() and scsi_resfree() functions have been replaced by scsi_destroy_pkt(9F).
ap Pointer to a scsi_address structure.
cmdlen The required length for the SCSI command descriptor block (CDB) in bytes.
statuslen The required length for the SCSI status completion block (SCB) in bytes.
dmatoken Pointer to an implementation-dependent object.
callback A pointer to a callback function, or NULL_FUNC or SLEEP_FUNC.
pkt Pointer to a scsi_pkt(9S) structure.
The scsi_pktalloc() function requests the host adapter driver to allocate a command packet. For commands that have a data transfer associated with them, scsi_resalloc() should be used.
ap is a pointer to a scsi_address structure. Allocator routines use it to determine the associated host adapter.
The cmdlen parameter is the required length for the SCSI command descriptor block. This block is allocated such that a kernel virtual address is established in the pkt_cdbp field of the allocated scsi_pkt structure.
statuslen is the required length for the SCSI status completion block. The address of the allocated block is placed into the pkt_scbp field of the scsi_pkt structure.
The dmatoken parameter is a pointer to an implementation dependent object which defines the length, direction, and address of the data transfer associated with this SCSI packet (command). The dmatoken must be a pointer to a buf(9S) structure. If dmatoken is NULL, no DMA resources are required by this SCSI command, so none are allocated. Only one transfer direction is allowed per command. If there is an unexpected data transfer phase (either no data transfer phase expected, or the wrong direction encountered), the command is terminated with the pkt_reason set to CMD_DMA_DERR. dmatoken provides the information to determine if the transfer count is correct.
callback indicates what the allocator routines should do when resources are not available:
NULL_FUNC Do not wait for resources. Return a NULL pointer.
SLEEP_FUNC Wait indefinitely for resources.
Other Values callback points to a function which is called when resources may have become available. callback must return either 0 (indicating that it attempted to allocate resources but again 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 scsi_pktfree() function frees the packet.
The scsi_resfree() function free all resources held by the packet and the packet itself.
Both allocation routines return a pointer to a scsi_pkt structure on success, or NULL on failure.
If callback is SLEEP_FUNC, then this routine can be called only from user or kernel context. Otherwise, it can be called from user, kernel, or interrupt context. The callback function may not block or call routines that block. Both deallocation routines can be called from user, kernel, or interrupt context.
See attributes(5) for a description of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|
attributes(5), scsi_dmafree(9F), scsi_dmaget(9F), buf(9S), scsi_pkt(9S)
Writing Device Drivers
The scsi_pktalloc(), scsi_pktfree(), scsi_resalloc(), and scsi_resfree() functions are obsolete and will be discontinued in a future release. The scsi_pktalloc() and scsi_resalloc() functions have been replaced by scsi_init_pkt(9F). The scsi_pktfree() and scsi_resfree() functions have been replaced by scsi_destroy_pkt(9F).