translating images

This document, "HP OpenVMS Migration Software for Alpha to Integrity Servers Guide to Translating Images," provides a comprehensive guide to migrating OpenVMS Alpha applications and VAX-translated (VESTed) images to OpenVMS Industry Standard 64 (I64) systems.

The core of the migration process involves the Alpha Environment Software Translator (AEST) utility. AEST takes an OpenVMS Alpha executable or shareable image, analyzes its code (identifying entry points, separating code/data, and detecting anomalies), and then generates a translated I64 image (named image_AV.EXE) along with a listing file (image_AV.LIS).

Key aspects of the guide include:

• Migration Strategies: Options range from rebuilding applications from source code (preferred for performance) to translating images directly (when source code is unavailable), or a hybrid approach combining both, leveraging OpenVMS I64's interoperability.
• Translated Image Environment (TIE): This runtime environment on OpenVMS I64 systems supports translated images, including the TIE$SHARE component which manages Alpha state, handles exception processing, and interprets any Alpha code AEST could not translate. Jacketing libraries mediate calls between translated and native images.
• Translation Process: AEST translates images automatically. It's recommended to first run AEST with the /AUDIT qualifier to assess translatability and identify source languages before attempting a full translation.
• Running Translated Images: Translated images are executed using the DCL RUN command (e.g., RUN image_AV). For applications involving shareable images, logical names may need to be defined or Alpha Image Information Files (.AIIF) used to redirect external references and map Alpha to I64 entry points.
• Shareable Image Interoperability: The manual details how to build and integrate translated and native shareable images. Native images interacting with translated ones require specific compiler (/TIE) and linker (/NONATIVE_ONLY) qualifiers to ensure proper call handling (jacketing) and symbol vector compatibility.
• Restrictions and Troubleshooting: Not all Alpha images can be translated (e.g., those with privileged code, user-written system services, or linked against very old OpenVMS versions). AEST provides return status messages (TRANSOK, TRANSWARN, TRANSERROR, TRANSFATAL) to indicate translation outcomes. Warnings might allow translation but advise careful review. Some complex issues, particularly related to custom thread management or direct kernel access, may not be detectable during translation and could manifest at runtime.

The document serves both users seeking to migrate their OpenVMS Alpha applications to I64 systems and developers working with translated shareable images, providing practical guidance and reference information for the AEST utility.