FreeBSD 6: open(/dev/lpt0, O_WRONLY) hangup "fixed"

[george+freebsd at m5p.com]

I've "solved" my /dev/lpt0 problem.  Here is what happened:

1. I observed that the problem is also happening on FreeBSD 6.0.
2. It isn't happening on 5.3.
3. I sprinkled some printf's into lptopen in sys/dev/ppbus/lpt.c.
4. I compiled a new kernel, stripping a whole bunch of stuff out
   of the generic kernel.  The problem went away.
5. I went back to the original lpt.c.  Still working.
6. I compiled another kernel, adding "device plip" back in.  The
   problem came back.

So the problem, whatever it is, seems to involve an interaction
between printing and plip.  Since I have printing working again,
debugging the problem is no longer a high priority for me.  But
if anyone has some suggestions for debugging, I would be happy to
try them this weekend.

Am I the only dinosaur still using a parallel port printer?  It
seems incredible to me that no one else using 6.0/6.1 could have
encountered this problem.  Even though I have "fixed" the problem,
it should probably be debugged properly, unless there's sentiment
for removing "device plip" from the generic kernel.
-- George Mitchell