.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This software was developed by the Computer Systems Engineering group
.\" at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
.\" contributed to Berkeley.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\"
.\"	from: Header: le.4,v 1.2 92/10/13 05:31:33 leres Exp
.\"	from: @(#)le.4	8.1 (Berkeley) 6/9/93
.\"	$NetBSD: le.4,v 1.3 1998/06/08 11:20:09 lukem Exp $
.\"
.Dd June 9, 1993
.Dt LE 4 sun3
.Os
.Sh NAME
.Nm le
.Nd AMD 7990 LANCE ethernet interface driver
.Sh SYNOPSIS
.Cd "le* at obio0 addr ? level ?"
.Cd "option LANCE_REVC_BUG"
.Sh DESCRIPTION
The 
.Nm
interface provides access to a 10 Mb/s
.Tn Ethernet
network via the
.Tn AMD
7990
.Tn LANCE
(Local Area Network Controller - Ethernet) chip set.
.Pp
Each of the host's network addresses
is specified at boot time with an
.Dv SIOCSIFADDR
.Xr ioctl 2 .
The
.Nm
interface employs the address resolution protocol described in
.Xr arp 4
to dynamically map between Internet and Ethernet addresses on the local
network.
.Sh BUGS
The old
.Tn LANCE
Revision C chips have a bug which causes garbage to be inserted in
front of the received packet occasionally.
The work-around is to ignore packets with an invalid destination
address (garbage will usually not match), by double-checking the
destination address of every packet in the driver.
This work-around is enabled with the
.Cd LANCE_REVC_BUG
kernel option.
It is unfortunately computationally costly, and
this precludes multicast support on Ethernet interfaces with that
chip in them.
.Pp
All sun3 systems are presumed to have this revision of the AM7990,
until proven otherwise.
Alas, the only way to prove what revision of the chip is in a particular
system is inspection of the date code on the chip package, with a list of
what chip revisions were fabricated between which dates.
A request has been sent to
.Tn AMD
for this information.
.Sh DIAGNOSTICS
.Bl -diag
.It "le%d: overflow"
More packets came in from the Ethernet than there was space in the
receive buffers.
Packets were missed.
.It "le%d: receive buffer error"
Ran out of buffer space, packet dropped.
.It "le%d: lost carrier"
The Ethernet carrier disappeared during an attempt to transmit.
It will finish transmitting the current packet,
but will not automatically retry transmission if there is a collision.
.It "le%d: excessive collisions, tdr %d"
Ethernet extremely busy or jammed,
outbound packets dropped after 16 attempts to retransmit.
.Pp
TDR is
.Qq Time Domain Reflectometry .
The
.Tn LANCE
TDR value is an internal counter of the interval between the start
of a transmission, and the occurrence of a collision.
This value can be used to determine the distance from the Ethernet
tap to the point on the Ethernet cable that is shorted or open
(unterminated).
.It "le%d: dropping chained buffer"
Packet didn't fit into a single receive buffer, packet dropped.
.It "le%d: transmit buffer error"
.Tn LANCE
ran out of buffer before finishing the transmission of a packet.
If this error occurrs, the driver software has a bug.
.It "le%d: underflow"
.Tn LANCE
ran out of buffer before finishing the transmission of a packet.
If this error occurrs, the driver software has a bug.
.It "le%d: controller failed to initialize"
Driver failed to start the AM7990
.Tn LANCE .
This is potentially a hardware failure.
.It "le%d: memory error"
.Tn RAM
failed to respond within the timeout when the
.Tn LANCE
wanted to read or write it.
This is potentially a hardware failure.
.It "le%d: receiver disabled"
The
.Tn LANCE
receiver was turned off due to an error.
.It "le%d: transmitter disabled"
The
.Tn LANCE
transmitter was turned off due to an error.
.El
.Sh SEE ALSO
.Xr ie 4 ,
.Xr intro 4 ,
.Xr inet 4 ,
.Xr arp 4
.Rs
.%R "Am79C90 - CMOS Local Area Network Controller for Ethernet"
.%D May 1994
.%N 17881
.%O Advanced Micro Devices
.Re