4.3 BSD bug - /sys/vaxmba/ht.c
Richard Stevens
stevens at hsi.UUCP
Fri Nov 7 01:33:52 AEST 1986
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.
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