Version 3.2 of the x-kernel uses either the Gnu C compiler (gcc) or the standard Unix compiler (cc). If you do not currently have Gnu C at your site, you can get a copy by doing anonymous FTP to prep.ai.mit.edu, and retrieving pub/gnu/gcc.xtar.
We recommend building the sunos version of the x-kernel with a gcc earlier than 2.0, if possible.