LE(4)							   BSD Kernel Interfaces Manual 						     LE(4)

NAME

     le -- AMD 7990, 79C90, 79C960, 79C970 LANCE Ethernet interface driver

SYNOPSIS

   ISA boards
     nele0 at isa? port 0x320 irq 9 drq 7    # NE2100
     le* at nele?
     bicc0 at isa? port 0x320 irq 10 drq 7   # BICC Isolan
     le* at bicc?
     depca0 at isa? port 0x300 iomem 0xc8000 iosiz 0x8000 irq 5 # DEC DEPCA
     le* at depca?
     le* at isapnp?			     # ISA Plug-and-Play adapters

   EISA boards
     depca* at eisa? slot ?		     # DEC DE422
     le* at depca?

   MCA boards
     le* at mca? slot ? 		     # SKNET Personal/MC2+

   PCI boards and mainboard adapters
     le* at pci? dev? function ?

   TURBOchannel PMAD-A or onboard (alpha, pmax)
     le* at tc? slot ? offset ?

   alpha
     le* at ioasic? offset ?

   amiga
     le* at zbus0

   atari
     le0 at vme0 irq 4	# BVME410
     le0 at vme0 irq 5	# Riebl/PAM

   hp300
     le* at dio? scode ?

   mvme68k
     le0 at pcc? ipl 3	# MVME147

   news68k
     le0 at hb0 addr 0xe0f00000 ipl 4

   newsmips
     le0 at hb0 addr 0xbff80000 level 1

   pmax
     le* at ioasic? offset ?
     le* at ibus0 addr ?

   sparc and sparc64
     le* at sbus? slot ? offset ?
     le* at ledma0 slot ? offset ?
     le* at lebuffer? slot ? offset ?

   sun3
     le0 at obio0 addr 0x120000 ipl 3
     options LANCE_REVC_BUG

   vax
     le0 at vsbus0 csr 0x200e0000

DESCRIPTION

     The le interface provides access to a Ethernet network via the AMD Am7990 and Am79C90 (CMOS, pin-compatible) LANCE (Local Area Network Con-
     troller - Ethernet) chip set.

     The le driver also supports PCnet-PCI cards based on the AMD 79c970 chipset, which is a single-chip implementation of a LANCE chip and PCI
     bus interface.

     Each of the host's network addresses is specified at boot time with an SIOCSIFADDR ioctl(2).  The le interface employs the Address Resolution
     Protocol (ARP) described in arp(4) to dynamically map between Internet and Ethernet addresses on the local network.

     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.

     The use of "trailer" encapsulation to minimize copying data on input and output is supported by the interface but offers no advantage on sys-
     tems with large page sizes.  The use of trailers is automatically negotiated with ARP.  This negotiation may be disabled, on a per-interface
     basis, with ifconfig(8).

HARDWARE

   amiga
     The le interface supports the following Zorro II expansion cards:

	   A2065      Commodore's Ethernet card, manufacturer 514, product 112

	   AMERISTAR  Ameristar's Ethernet card, manufacturer 1053, product 1

	   ARIADNE    Village Tronic's Ethernet card, manufacturer 2167, product 201

     The A2065 and Ameristar Ethernet cards support only manual media selection.

     The Ariadne card supports a software media selection for its two different connectors:

     10Base2/BNC     also known as thinwire-Ethernet

     10BaseT/UTP     also known as twisted pair

     The Ariadne card uses an autoselect between UTP and BNC, so it uses UTP when an active UTP line is connected or otherwise BNC.  See
     ifmedia(4) for media selection options for ifconfig(8).

   ISA
     The ISA-bus Ethernet cards supported by the le interface are:

	   BICC Isolan
	   Novell NE2100
	   Digital DEPCA

   EISA
     The EISA-bus Ethernet cards supported by the le interface are:

	   DEC DE422

   MCA
     The MCA-bus Ethernet cards supported by the le interface are:

	   SKNET Personal MC2
	   SKNET MC2+

   pmax
     All LANCE interfaces on DECstations are supported, as are interfaces on Alpha AXP machines with a TURBOchannel bus.

     No support is provided for switching between media ports.	The DECstation 3100 provides both AUI and BNC (thinwire or 10BASE2) connectors.
     Port selection is via a manual switch and is not software configurable.

     The DECstation model 5000/200 PMAD-AA baseboard device provides only a BNC connector.

     The ioasic baseboard devices and the PMAD-AA TURBOchannel option card provide only an AUI port.

   sparc
     The Sbus Ethernet cards supported by the le interface include:
	   SBE/S
		 SCSI and Buffered Ethernet (sun part 501-1860)
	   FSBE/S
		 Fast SCSI and Buffered Ethernet (sun part 501-2015)
	   Antares SBus 10Base-T Ethernet
		 Buffered Ethernet (antares part 20-050-1007)

     Interfaces attached to an ledma0 on SPARC systems typically have two types of connectors:

	   AUI/DIX	       Standard 15 pin connector

	   10BaseT	       UTP, also known as twisted pair

     The appropriate connector can be selected by supplying a media parameter to ifconfig(8).  The supported arguments for media are:

	   10base5/AUI	       to select the AUI connector, or

	   10baseT/UTP	       to select the UTP connector.

     If a media parameter is not specified, a default connector is selected for use by examining all media types for carrier.  The first connector
     on which a carrier is detected will be selected.  Additionally, if carrier is dropped on a port, the driver will switch between the possible
     ports until one with carrier is found.

DIAGNOSTICS

     le%d: overflow  More packets came in from the Ethernet than there was space in the receive buffers.  Packets were missed.

     le%d: receive buffer error  Ran out of buffer space, packet dropped.

     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.

     le%d: excessive collisions, tdr %d  Ethernet extremely busy or jammed, outbound packets dropped after 16 attempts to retransmit.

     TDR is "Time Domain Reflectometry".  The 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).

     le%d: dropping chained buffer  Packet didn't fit into a single receive buffer, packet dropped.  Since the le driver allocates buffers large
     enough to receive the maximum size Ethernet packet, this means some other station on the LAN transmitted a packet larger than allowed by the
     Ethernet standard.

     le%d: transmit buffer error  LANCE ran out of buffer before finishing the transmission of a packet.  If this error occurs, the driver soft-
     ware has a bug.

     le%d: underflow  LANCE ran out of buffer before finishing the transmission of a packet.  If this error occurs, the driver software has a bug.

     le%d: controller failed to initialize  Driver failed to start the AM7990 LANCE.  This is potentially a hardware failure.

     le%d: memory error  RAM failed to respond within the timeout when the LANCE wanted to read or write it.  This is potentially a hardware fail-
     ure.

     le%d: receiver disabled  The LANCE receiver was turned off due to an error.

     le%d: transmitter disabled  The LANCE transmitter was turned off due to an error.

SEE ALSO

     arp(4), ifmedia(4), inet(4), intro(4), mca(4), ifconfig(8)

     Am79C90 - CMOS Local Area Network Controller for Ethernet, 17881, May 1994, Advanced Micro Devices.

HISTORY

     The pmax le driver is derived from a le driver that first appeared in 4.4BSD.  Support for multiple bus attachments first appeared in
     NetBSD 1.2.

     The Amiga le interface first appeared in NetBSD 1.0

     The Ariadne Ethernet card first appeared with the Amiga ae interface in NetBSD 1.1 and was converted to the Amiga le interface in NetBSD 1.3

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 is enabled with the LANCE_REVC_BUG kernel option.

     When LANCE_REVC_BUG is enabled, the le driver executes one or two calls to an inline Ethernet address comparison function for every received
     packet.  On the mc68000 it is exactly eight instructions of 16 bits each.	There is one comparison for each unicast packet, and two compar-
     isons for each broadcast packet.

     In summary, the cost of the LANCE_REVC_BUG option is:
     1.   loss of multicast support, and
     2.   eight extra CPU instructions per received packet, sometimes sixteen, depending on both the processor, and the type of packet.

     All sun3 systems are presumed to have this bad 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, to compare against a list of what chip revisions were
     fabricated between which dates.

     Alas, the Am7990 chip is so old that AMD has "de-archived" the production information about it; pending a search elsewhere, we don't know how
     to identify the revision C chip from the date codes.

     On all pmax front-ends, performance is impaired by hardware which forces a software copy of packets to and from DMA buffers.  The ioasic
     machines and the DECstation 3100 must copy packets to and from non-contiguous DMA buffers.  The DECstation 5000/200 and the PMAD-AA must copy
     to and from an onboard SRAM DMA buffer.  The CPU overhead is noticeable, but all machines can sustain full 10 Mb/s media speed.

BSD
								  April 27, 2001							       BSD