M. Warner Losh <imp@bsdimp.com> comments;

> My guess is so that you can either map the memory low or high.

Yes, they want to mimic MIPS/PPC way, but the feature makes the
complicated story worse, and I think not a relevant feature in practice.
It would be nicer just to have "reset entry at high addr", not the entire
exception vector.

Toru Nishimura/ALKYL Technology