The RPMS were built on:

 alpha: Red Hat 5 and Red Hat 6.
 arm:   Disc image 15 from netwinder.org (roughly = Red Hat).
 ppc:   LinuxPPC 1999 (Q3, alias V2).
 sparc: ???
 x86:   Red Hat 6.

The sparc RPMs were made by Eddie C. Dost (ecd@skynet.be).