The AIX Fibre Channel Protocol for SCSI (FCP) subsystem has two parts:
The FCP adapter device driver is designed to shield you from having to communicate directly with the system I/O hardware. This gives you the ability to successfully write a FCP device driver without having a detailed knowledge of the system hardware. You can look at the FCP subsystem as a two-tiered structure in which the adapter device driver is the bottom or supporting layer. As a programmer, you need only worry about the upper layer. This chapter only discusses writing a FCP device driver, because the FCP adapter device driver is already provided in AIX.
The FCP adapter device driver, or lower layer, is responsible only for the communications to and from the FCP bus, and any error logging and recovery. The upper layer is responsible for all of the device-specific commands. The FCP device driver should handle all commands directed towards its specific device by building the necessary sequence of I/O requests to the FCP adapter device driver in order to properly communicate with the device.
These I/O requests contain the FCP commands that are needed by the FCP device. One important aspect to note is that the FCP device driver cannot access any of the adapter resources and should never try to pass the FCP commands directly to the adapter, since it has absolutely no knowledge of the meaning of those commands.
The following topics are covered in this chapter:
For more information on Physical Volume Identifiers (PVID), see Making an Available Disk a Physical Volume" in AIX Version 4.3 System Management Guide: Operating System and Devices.