An HBA driver must allocate a scsi_hba_tran(9S) structure during attach(9E) and initialize the vectors in this transport structure to point to the required HBA driver entry points. This scsi_hba_tran(9S) structure is then passed into scsi_hba_attach_setup(9F).
The scsi_hba_tran(9S) structure contains a tran_hba_private field, which may be used to refer to the HBA driver's per-instance state.
Each scsi_address(9S) structure contains a pointer to the scsi_hba_tran(9S) structure and also provides the target (a_target) and logical unit (a_lun) addresses for the particular target device. Because every HBA driver entry point is passed a pointer to the scsi_address(9S) structure, either directly or indirectly through the scsi_device(9S) structure, the HBA driver can reference its own state and can identify the target device being addressed.
Figure 14-3 illustrates the HBA data structures for transport operations.