We have several SM cards with DEC 21140-AB ethernet chips in P6's
running NetBSD-1.2.1. Recently we moved to new quarters which have,
among other things, a Bay 100Mbit switch which is full duplex capable
(our old 100Mbit hub could only do 1/2 duplex. But when we make the
ports connecting to our NetBSD boxes full duplex, performance gets
really *horrible* (pathchar goes so slow that we just gave up on trying
to get numbers out of it); this continues even if I power cycle all the
machines to make sure any necessary auto-detecting gets done.

So is there some parameter I need to give to ifconfig, or a kernel
compile option I need to define, to get the driver to work correctly in
full duplex mode? (again, keeping in mind this is 1.2.1 and not -current).