OpenVMS Alpha Guide to Upgrading Privileged-Code Applications

This HP OpenVMS Guide, published in January 2005, assists system programmers in upgrading privileged-code applications and device drivers for OpenVMS Alpha Version 7.0 and later, and OpenVMS I64 Version 8.2. It specifically addresses source-code changes required due to:

1. OpenVMS Alpha 64-bit Virtual Addressing: This involved significant changes to privileged interfaces and data structures to expand virtual address space (P0, P1, P2, S2) to 8TB and support increased physical memory.
2. OpenVMS Alpha Kernel Threads Support: This introduced extended process scheduling for multi-CPU concurrency, leading to fundamental changes in the OpenVMS process structure, particularly the Process Control Block (PCB).
3. OpenVMS I64 Infrastructure Changes: These include accommodating 50-bit physical addressing and changes to Page Frame Number (PFN) fields, which become 64-bit on I64.

The guide is divided into:

• Part I: Details privileged-code changes for OpenVMS Alpha.
• Part II: Covers privileged-code changes for OpenVMS I64, encouraging common code development with Alpha.
• Appendices: Provide descriptions of I/O routines, data structures, and kernel threads routines/macros.

Key recommendations include recompiling and relinking applications to identify necessary source changes, particularly for handling 64-bit pointers, modified data structures (e.g., IRP, PCB, PFN database entries), and updated I/O and memory management routines. Non-privileged applications and OpenVMS VAX systems are not affected.