On Sun, 15 Mar 1998, Erik E. Fair wrote:

> How is _SUN3_ or _SUN3X_ supposed to get defined for the purpose of
> compiling these modules? One of those defines is required in order to get
> the right pmap.h file (pmap3.h or pmap3x.h). However, it looks like those
> defines are strictly animals of the config system for the kernel...

They are defined by adding pre-processor command line arguments (-Dxxxx) 
at compile time.  When /usr/sbin/config generates a Makefile for the
kernel, it includes the correct SUN3 or SUN3X symbol on each command
line, based on directives in the kernel configuration file.  (option
SUN3X)

-J