The main difference between the 4.3/4.4 version and the netbsd version
(w.r.t. hilread) is probably the "clist" interface (q_to_b, b_to_q).
That might be the first place to look.  I would suggest defining DEBUG
and turning on HDB_EVENTS in hildebug.  That will print out a message
for every interrupt you get.  That way you can determine if you are
even getting interrupts.  If you are, then it is something in the read
or select mech. that is causing the problem.

Re: the shared queue interface, I may have never implemented it in 4.4
since it wasn't used.

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