With -current beginning about 7/31 and continuing through this morning's
sup, I've been having some problems with the serial ports.  In particular,
it appears that nothing is coming in; perhaps nothing going out as well.
Same problem occurs on a GENERIC kernel built by Allen Briggs.

Scenario:  with standard AT type modem on ser0, set line speed and various
other parameters: stty -f /dev/tty00 ospeed 38400 ispeed 38400 -parenb
-clocal crtscts

(the same options I would normally use for a ppp connection)

Then, cu -l /dev/tty00
I get a "Connected." response, but typing AT<cr> results in no response.

The exact same sequence as above on a system built from a 7/29 or 7/30 sup
works just fine, and shows the modem's response "OK".

I've placed lots of printf's into various places in the ser.c code, and
I've verified that the driver is getting interrupts.  But I'm not sure
they're the right interrupts, since they happen often at the wrong time,
and never at the right time.  (Meaning, although the driver's serwrite
routine gets called, there's never an output silo empty interrrupt, for
example.  And, even before I type anything at the modem, there're many
receive char ready interrupts, but mostly with null characters.)

I'd love to have a real terminal to put on the line, instead of the modem,
but alas I don't have one.

Anyone got any ideas how to proceed from here?  Has anyone else seen this?

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