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From: stevens@hsi.UUCP (Richard Stevens)
Newsgroups: net.bugs.4bsd
Subject: 4.3 BSD bug - /sys/vaxmba/ht.c
Message-ID: <444@hsi.UUCP>
Date: Thu, 6-Nov-86 10:33:52 EST
Article-I.D.: hsi.444
Posted: Thu Nov  6 10:33:52 1986
Date-Received: Sat, 8-Nov-86 18:35:54 EST
Distribution: net
Organization: Health Systems Int., New Haven, CT.
Lines: 21

Description:
	Reading past the "logical end-of-tape" using the ht driver
	will crash the system.  We are running an Emulex TC7000
	with a Kennedy 9400 tape drive on a VAX-11/785 with the
	vanilla 4.3 BSD ht.c driver.  Unfortunately we occasionally
	get tapes written on "other" systems that aren't terminated
	by a double EOF, and the utilities we use to process these
	tapes expect a double EOF.

Repeat-By:
	Take a brand new tape.  Write a single EOF using mt(1).
	Leave the tape positioned after that EOF and do a dd(1)
	to read from that point on.  The tape will start reading
	and after about 10 seconds you'll get either a "protection fault"
	panic or a "segmentation fault" panic.  The panic always prints
	the pc as _htustart+0xce:

		htustart+cb:	movl	(sp)+,r0	/ error here
		htustart+ce:	movc5	$0,(r3),$0,r0,(r3)

	I do not have a fix for this problem.