20.1.1 Single-Channel SCSI Adapters

If the SCSI adapter supports one channel, then the SCSI host controller driver performs the following:

  • Install Extended SCSI Pass Thru Protocol onto the controller handle for the

    SCSI host controller.

  • Set the logical attribute for the SCSI channel in the mode structure.

  • Set the physical attribute for the SCSI channel in the mode structure.

The following figure shows an example implementation on a single-channel SCSI adapter. The green layer represents the SCSI host controller driver.

Figure 22-Sample SCSI driver stack on single-channel adapter

Because there is only one SCSI channel, the SCSI driver can simply implement one instance of the Extended SCSI Pass Thru Protocol. The platform firmware provides the SCSI Bus Driver and SCSI Disk Driver that complete the driver stack by performing the following actions:

  • Scan for SCSI targets on the SCSI channel and create child handles.

  • Install Device Path Protocol to each child handle.

  • Install SCSI I/O Protocol to each child handle.

  • Install I/O abstraction such as the Block I/O Protocol to each child handle.