Date: Mon, 02 Dec 1996 00:32:44 +0100 From: Stefan Schmidt <schmidts@informatik.tu-muenchen.de> To: bugs@freebsd.org Subject: lp0 problems Message-ID: <32A2159B.41C67EA6@informatik.tu-muenchen.de>
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Hi,
I recently connected a laptop (2.2-961014-SNAP) and a
pc (2.1.5-RELEASE) through lp0 w/ laplink cable.
The following problems occured:
(1) the 2.2-961014-SNAP machine spontaneously
freezes/panics/reboots when sending/receiving over
lp0. as I tried to spot this bug:
(2) tcpdump on lp0 didn't work
after looking at /sys/i386/isa/lpt.c and searching the mailing-lists,
it seems that a suggested fix from Bill Fenner <fenner@parc.xerox.com>
hasn't been applied yet. (from Mon, 22 Jan 1996 12:34:20 PST)
the problem is a off-by-2 error when sending data to bpf.
another problem is: in lpoutput(), the to-be-sent mbuf is
manipulated during output to lpt. therefore the following
call to bpf_mtap() handles a corrupted mbuf to bpf.
(tcpdump may segfault)
after applying some quick&dirty patches to lpt.c (fixing the
off-by-2 errors and calling bpf_mtap before the mbufs are corrupted)
tcpdump an lp0 works.
stefan
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