Open-standard development environment for IBM System z9 host firmware

When the PL8 64-bit GNU compiler collection front end was introduced with the IBM z990 system, it laid the foundation to move toward an open-standard development environment for the i390 layer of IBM System ze host firmware. However, when the z990 system was developed, the proprietary project development library system and the table of contents object file format for i390 code were still being used. With the IBM System z9e, we have moved to a fully open-standard development environment. This paper describes the steps we took to get there, to improve code performance, development efficiency, and regression testing, and to develop base functionality for important System z9 features such as enhanced driver maintenance. We also discuss plans to further enhance the development environment for future systems.