I am working on the build system for a rather large and old industrial software. As a result of the build, it spits out around 20 rpms (built from scratch with rpmbuild, built from scratch via setup.py, patched and re-built src.rpms).
Running the build on different machines (all Centos 6.4 & 6.9) produces inconsistent results with respect to the final architecture of the packages. One machine spits out all i386 packages. On other machines some of the packages come out i386 while some come out i686. Results are consistent on any one machine, but inconsistent between different machines.
My question is:
What factors control whether rpmbuild produces i386 packages vs. i686 packages?