There are various fragments of code around the tree that are
conditionalised on HYDRA being defined, apparently in support of the
Simtec Hydra multi-processor board.  As far as I can tell, the
configuration glue for this was removed from files.arm32 in 1997 (rev
1.29) and the main hydrabus driver (in arch/arm32/mainbus/exp/hydra.c)
never got committed.

Would there be any problem with garbage-collecting all the code that's
protected by this ifdef?

-- 
Ben Harris                                                   <bjh21@netbsd.org>
Portmaster, NetBSD/arm26               <URL:http://www.netbsd.org/Ports/arm26/>