.\"	$NetBSD: le.4,v 1.22 2004/10/04 19:12:52 rumble Exp $
.\"
.\"-
.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
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.\" This software was developed by the Computer Systems Engineering group
.\" at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
.\" contributed to Berkeley.
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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
.\" $FreeBSD: /repoman/r/ncvs/src/share/man/man4/le.4,v 1.2 2006/02/02 14:57:00 marius Exp $
.\" $DragonFly: src/share/man/man4/man4.i386/lnc.4,v 1.7 2008/05/02 02:05:06 swildner Exp $
.\"
.Dd July 7, 2006
.Dt LNC 4 i386
.Os
.Sh NAME
.Nm lnc
.Nd AMD Am7900 LANCE and Am79C9xx PCnet Ethernet interface driver
.Sh SYNOPSIS
.Cd "device lnc"
.Sh DESCRIPTION
The
.Nm
driver provides support for the AMD family of Lance/PCnet Ethernet NICs
including the Am7990 and Am79C960.
.Pp
The
.Nm
driver also supports PCnet adapters based on the
.Tn AMD 79C9xx
family of chips, which are single-chip implementations of a
.Tn LANCE
chip and a DMA engine.
This includes a superset of the
.Tn PCI
bus Ethernet chip sets supported by the
.Xr pcn 4
driver.
The
.Nm
driver treats all of these
.Tn PCI
bus Ethernet chip sets as an
.Tn AMD Am79C970 PCnet-PCI
and does not support the additional features like the MII bus and burst mode of
.Tn AMD Am79C971 PCnet-FAST
and greater chip sets.
Thus the
.Xr pcn 4
driver should be preferred for the latter.
.Pp
The
.Nm
driver supports reception and transmission of extended frames for
.Xr vlan 4 .
Selective reception of multicast Ethernet frames is provided by a 64-bit mask;
multicast destination addresses are hashed to a bit entry using the Ethernet
CRC function.
.Sh HARDWARE
.\" .Ss ISA
.\" The
.\" .Tn ISA
.\" bus Ethernet cards supported by the
.\" .Nm
.\" driver are:
.\" .Pp
.\" .Bl -bullet -compact
.\" .It
.\" .Tn BICC Isolan
.\" .It
.\" .Tn Novell NE2100
.\" .It
.\" .Tn Digital DEPCA
.\" .El
.\" .Ss EISA
.\" The
.\" .Tn EISA
.\" bus Ethernet cards supported by the
.\" .Nm
.\" driver are:
.\" .Pp
.\" .Bl -bullet -compact
.\" .It
.\" .Tn DEC DE422
.\" .El
.\" .Ss MCA
.\" The
.\" .Tn MCA
.\" bus Ethernet cards supported by the
.\" .Nm
.\" driver are:
.\" .Pp
.\" .Bl -bullet -compact
.\" .It
.\" .Tn SKNET Personal MC2
.\" .It
.\" .Tn SKNET MC2+
.\" .El
.Ss PCI
The
.Tn PCI
bus Ethernet chip sets supported by the
.Nm
driver are:
.Pp
.Bl -bullet -compact
.It
.Tn AMD Am53C974/Am79C970/Am79C974 PCnet-PCI
.It
.Tn AMD Am79C970A PCnet-PCI II
.It
.Tn AMD Am79C971 PCnet-FAST
.It
.Tn AMD Am79C972 PCnet-FAST+
.It
.Tn AMD Am79C973/Am79C975 PCnet-FAST III
.It
.Tn AMD Am79C976 PCnet-PRO
.It
.Tn AMD Am79C978 PCnet-Home
.El
.Pp
The
.Nm
driver supports the following media types with these chip sets:
.Bl -tag -width xxxxxxxxxxxxxxxxxxxx
.It autoselect
Enable autoselection of the media type.
.It 10baseT/UTP
Select UTP media.
.It 10base5/AUI
Select AUI/BNC media.
.El
.Pp
The following media option is supported with these media types:
.Bl -tag -width xxxxxxxxxxxxxxxxxxxx
.It full-duplex
Select full duplex operation.
.El
.Pp
Note that unlike the
.Xr pcn 4
driver, the
.Nm
driver does not support selecting 100Mbps (Fast Ethernet) media types.
.Pp
For further information on configuring media types and options, see
.Xr ifconfig 8 .
.Sh DIAGNOSTICS
.Bl -diag
.It "lnc%d: overflow"
More packets came in from the Ethernet than there was space in the
.Tn LANCE
receive buffers.
Packets were missed.
.It "lnc%d: receive buffer error"
The
.Tn LANCE
ran out of buffer space, packet dropped.
.It "lnc%d: lost carrier"
The Ethernet carrier disappeared during an attempt to transmit.
The
.Tn LANCE
will finish transmitting the current packet,
but will not automatically retry transmission if there is a collision.
.It "lnc%d: excessive collisions, tdr %d"
The Ethernet was extremely busy or jammed,
outbound packets were dropped after 16 attempts to retransmit.
.Pp
TDR
is the abbreviation of
.Qq Time Domain Reflectometry .
The optionally reported 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 "lnc%d: dropping chained buffer"
A packet did not fit into a single receive buffer and was dropped.
Since the
.Nm
driver allocates buffers large enough to receive maximum sized Ethernet
packets, this means some other station on the LAN transmitted a packet
larger than allowed by the Ethernet standard.
.It "lnc%d: transmit buffer error"
The
.Tn LANCE
ran out of buffer space before finishing the transmission of a packet.
If this error occurs, the driver software has a bug.
.It "lnc%d: underflow"
The
.Tn LANCE
ran out of buffer space before finishing the transmission of a packet.
If this error occurs, the driver software has a bug.
.It "lnc%d: controller failed to initialize"
Driver failed to start the
.Tn LANCE .
This is potentially a hardware failure.
.It "lnc%d: memory error"
RAM failed to respond within the timeout when the
.Tn LANCE
wanted to read or write it.
This is potentially a hardware failure.
.It "lnc%d: receiver disabled"
The receiver of the
.Tn LANCE
was turned off due to an error.
.It "lnc%d: transmitter disabled"
The transmitter of the
.Tn LANCE
was turned off due to an error.
.El
.Sh SEE ALSO
.Xr arp 4 ,
.Xr ifmedia 4 ,
.Xr intro 4 ,
.Xr netintro 4 ,
.Xr pcn 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 2.2 ,
it was replaced in
.Dx 1.5
with the
.Xr le 4
driver from
.Fx 6.1
which was in turn ported from
.Nx .
The
.Nx
driver was derived from the
.Xr le 4 driver in
.Bx 4.4 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was ported to
.Fx
by
.An "Marius Strobl" Aq marius@FreeBSD.org
and later ported to
.Dx
by
.An "Bill Marquette" Aq bill.marquette@gmail.com .
.\" .Sh BUGS
.\" The Am7990 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 can be enabled with the
.\" .Dv LANCE_REVC_BUG
.\" kernel option.
.\" .Pp
.\" When
.\" .Dv LANCE_REVC_BUG
.\" is enabled, the
.\" .Nm
.\" driver executes one or two calls to an inline Ethernet address comparison
.\" function for every received packet.
.\" There is one comparison for each unicast packet, and two comparisons for
.\" each broadcast packet.
.\" .Pp
.\" In summary, the cost of the LANCE_REVC_BUG option is:
.\" .Bl -enum -compact
.\" .It
.\" loss of multicast support, and
.\" .It
.\" eight extra
.\" .Tn CPU
.\" instructions per received packet, sometimes sixteen, depending on both the
.\" processor, and the type of packet.
.\" .El
.\" .Pp
.\" Alas, the Am7990 chip is so old that
.\" .Tn AMD
.\" has
.\" .Qq de-archived
.\" the production information about it; pending a search elsewhere, we do not
.\" know how to identify the revision C chip from the date codes.