build flags for a 386DX (5.1)

[escalated from -questions]

Hi folks-

I am setting up FreeBSD 5.1-RELEASE on a 386DX.  I'm mostly doing it as a 
learning exercise (or perhaps because I'm a masochist), but the machine may 
be used as a firewall at some point.  I have the OS installed with a custom 
kernel, and things are actually going quite well.

There are (of course) some problems though.  Most of the userland utilities 
work great, but some just dump core.  The one I miss in particular is groff 
(for manpages, etc).  I suspect that the problems are a result of CPU 
instructions that the poor 386 doesn't understand.

I do have a separate build machine (soon to be running 5.1 as well), so I'd 
like to recompile everything (kernel, world, and 
ports-to-be-made-into-packages) for the 386 with the appropriate flags to 
gcc and friends.  Hopefully that will take care of the issues I'm seeing.

So my question is, what flags should I use and where should I put them?  I'd 
like to be able to switch easily between builds for the 386 and "normal" 
builds (for everything else).  Can I just put an override in /etc/make.conf 
or do I have to futz with /usr/share/mk/bsd.cpu.mk?  (In the case of the 
latter, detailed hints would be appreciated.. I don't grok Make all that 
well yet.)

Thanks,

JN