Linux on IBM Z runs on the s390x architecture. Unlike x86, the s390x architecture is big-endian. Many open source projects only test against little-endian systems, so there may be endian-related bugs lurking. For example, in the Ruby implementation of Protocol Buffers, we fixed a handful of big-endian bugs.
There are several ways to develop for s390x. You can use:
- A LinuxONE virtual server.
Use the following commands to spin up an emulated s390x virtual machine with Docker:
docker run --rm --privileged multiarch/qemu-user-static --reset -p yes docker run --rm -it s390x/ubuntu bash
Note that the QEMU virtual machine is usually slower than a LinuxONE machine.
Bazel is needed by a number of Google projects, such as Protocol Buffers. When compiling from source, you might run into these fatal compiler warnings. There is a workaround to disable those warnings. In addition, IBM posted these instructions.
To build Omnibus GitLab for s390x, you can use this Dockerfile template. Generate the Dockerfile with: