The tran_init_pkt(9E) entry point must allocate a scsi_pkt(9S) structure if pkt is NULL through scsi_hba_pkt_alloc(9F).
scsi_hba_pkt_alloc(9F) allocates the following:
SCSI CDB of length cmdlen
SCSI status completion area of length statuslen
Per-packet target driver private data area of length tgtlen
Per-packet HBA driver private data area of length hbalen
The scsi_pkt(9S) structure members, as well as pkt itself, must be initialized to zero except for the following members: pkt_scbp (status completion), pkt_cdbp (CDB), pkt_ha_private (HBA driver private data), pkt_private (target driver private data). These members are pointers to memory space where the values of the fields are stored, as illustrated in Figure 15–5. For more information, refer to scsi_pkt Structure.
Example 15–2 provides an example of allocation and initialization of a scsi_pkt(9S) structure.
static struct scsi_pkt * isp_scsi_init_pkt( struct scsi_address *ap, struct scsi_pkt *pkt, struct buf *bp, int cmdlen, int statuslen, int tgtlen, int flags, int (*callback)(), caddr_t arg) { struct isp_cmd *sp; struct isp *isp; struct scsi_pkt *new_pkt; ASSERT(callback == NULL_FUNC || callback == SLEEP_FUNC); isp = (struct isp *)ap->a_hba_tran->tran_hba_private; /* * First step of isp_scsi_init_pkt: pkt allocation */ if (pkt == NULL) { pkt = scsi_hba_pkt_alloc(isp->isp_dip, ap, cmdlen, statuslen, tgtlen, sizeof (struct isp_cmd), callback, arg); if (pkt == NULL) { return (NULL); } sp = (struct isp_cmd *)pkt->pkt_ha_private; /* * Initialize the new pkt */ sp->cmd_pkt = pkt; sp->cmd_flags = 0; sp->cmd_scblen = statuslen; sp->cmd_cdblen = cmdlen; sp->cmd_dmahandle = NULL; sp->cmd_ncookies = 0; sp->cmd_cookie = 0; sp->cmd_cookiecnt = 0; sp->cmd_nwin = 0; pkt->pkt_address = *ap; pkt->pkt_comp = (void (*)())NULL; pkt->pkt_flags = 0; pkt->pkt_time = 0; pkt->pkt_resid = 0; pkt->pkt_statistics = 0; pkt->pkt_reason = 0; new_pkt = pkt; } else { sp = (struct isp_cmd *)pkt->pkt_ha_private; new_pkt = NULL; } /* * Second step of isp_scsi_init_pkt: dma allocation/move */ if (bp && bp->b_bcount != 0) { if (sp->cmd_dmahandle == NULL) { if (isp_i_dma_alloc(isp, pkt, bp, flags, callback) == 0) { if (new_pkt) { scsi_hba_pkt_free(ap, new_pkt); } return ((struct scsi_pkt *)NULL); } } else { ASSERT(new_pkt == NULL); if (isp_i_dma_move(isp, pkt, bp) == 0) { return ((struct scsi_pkt *)NULL); } } } return (pkt); }