OpenJDK comes with a zero assembler port called Zero. Back in 2009 when Zero was originally developed by Gary Benson, OpenJDK was available only on x86, x86_64 and SPARK. Despite recent JIT ports, such as the AArch64 and ppc/aix port, Zero still remains relevant for many Linux distributions. For example, at Red Hat we build and use the OpenJDK zero variant on PPC/PPC64 and s390/s390x. What's more it's a useful tool for getting new JIT ports built from source using free software.

This talk will give a brief summary what Zero is and how it works. It will cover some of the recently discovered issues with sustaining the Zero port, how we try to catch them early and it will explain our experience with pushing fixes upstream. There will also be examples how this effort benefits the OpenJDK ecosystem as a whole.