Whoops. Jason Thorpe tells me there are some broken bits in -current
for pmaxes.  I misplaced a few things; I'll fix them soon if Jason
hasn't got to them first.  Thanks, jason.

I've also run into some problems with serial consoles and the latest
scc code.  Doing a shutdown can hang a machine.  The problem is
somewhere in the scc code: either in the dialin/dialout support in
sccopen(), the spls() around that code, or in my incorporation of
Takuya Koumoto's work on the scc driver.  

Backing out both of those changes fixes the problem, i havent figured
out yet which it is.  I should get a fix for that in the tree in a day
or so.

Meanwhile I'm still actively cobbling together newer, better, cleaner,
I/O-bus autoconfiguration code for the pmax. The goal here is to clean
up the pmax so we can share drivers between the ALpha port and the
pmax: use a PMAZ-A on an Alpha or the TCDS TC cards in a DECstation.
I'm also hoping the changes will make feasible to use, e.g., the 3100
graphics drivers and rcons in vaxstation 3100s.

These are pervasive changes.  I'm testing them as I go but there will
doubtless be glitches.  If you're tracking -current, expect things to
be lightly broken from time to time as this work gets committed.

The good news is that since the changes are (for now) to the config
machinery rather than to drivers themselves, if a machine boots at
all, it should be okay.