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Path: utzoo!watmath!clyde!floyd!harpo!decvax!mcnc!ncsu!mcm
From: mcm@ncsu.UUCP (Mike Mitchell)
Newsgroups: net.unix-wizards,net.periphs
Subject: device interrupts during config (4.1bsd)
Message-ID: <2550@ncsu.UUCP>
Date: Thu, 5-Apr-84 17:07:43 EST
Article-I.D.: ncsu.2550
Posted: Thu Apr  5 17:07:43 1984
Date-Received: Sat, 7-Apr-84 04:01:34 EST
Organization: N.C. State University, Raleigh
Lines: 17

We have just installed a new line printer interface on our VAX 11/780
running 4.1 BSD.  The new controller presents a constant interrupt
if interrupts are enabled & the printer is ready to accept a character.
During auto-configure, interrupts are enabled and the system goes into
a tight loop trying to dismiss the interrupt.  Has anyone seen this
problem before?  I've fixed the problem by setting the priority to zero
before the probe routine is called and modifying locore.s so that during
autoconfigure stray interrupts return with the old priority set to the
level of the interrupting device.  This allows only one interrupt per
device, even if the interrupt line is held.

I find it strange that the line printer driver has a comment that it
has been fixed to support interfaces that interrupt constantly, yet
the autoconfigure code breaks when a device interrupts constantly.

	Mike Mitchell
	mcnc!ncsu!mcm