Writing Device Drivers for the SCSI CAM Architecture Interfaces Feb94

This document, "Writing Device Drivers for the SCSI/CAM Architecture Interfaces" on DEC OSF/1, is a comprehensive guide for systems programmers.

It provides detailed information on how to develop device drivers for the SCSI Common Access Method (CAM) architecture within the DEC OSF/1 operating system, emphasizing hardware independence through the Transport (XPT) and SCSI Interface Module (SIM) layers.

Key areas covered include:

• SCSI/CAM Software Architecture: An overview of the CAM model, including User Agent drivers, various peripheral device driver types (common, generic, disk, tape, CD-ROM/AUDIO), the configuration driver, and the XPT and SIM layers.
• Data Structures: Detailed descriptions of CAM Control Blocks (CCBs), I/O data structures, and other essential data structures used by drivers.
• Routines and Modules: Explanations of common and generic routines for I/O operations, queue manipulation, CCB management, command building, buffer management, and loadable drivers.
• Configuration: How the Configuration driver initializes the CAM subsystem, scans the SCSI bus, and manages device information.
• Error Handling and Debugging: Facilities for error logging, event reporting, and debugging SCSI/CAM peripheral device drivers.
• Special I/O Interface: A standardized method for processing special SCSI I/O control commands.

The manual includes numerous code examples, header file references, and a description of the SCSI/CAM Utility Program (SCU) for maintenance and diagnostics, making it a practical resource for developers.