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LE(4) NetBSD Kernel Interfaces Manual LE(4)
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by Kimmo Suominen.
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le -- AMD 7990, 79C90, 79C960 LANCE Ethernet interface driver
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
depca* at eisa? slot ? # DEC DE422
le* at depca?
le* at mca? slot ? # SKNET Personal/MC2+
TURBOchannel PMAD-A or onboard (alpha, pmax)
le* at tc? slot ? offset ?
le* at ioasic? offset ?
le* at zbus0
le0 at vme0 irq 4 # BVME410
le0 at vme0 irq 5 # Riebl/PAM
le* at dio? scode ?
le0 at mainbus0
le0 at pcc? ipl 3 # MVME147
le0 at hb0 addr 0xe0f00000 ipl 4
le0 at hb0 addr 0xbff80000 level 1
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 ?
le0 at obio0 addr 0x120000 ipl 3
le0 at vsbus0 csr 0x200e0000
The le interface provides access to a Ethernet network via the AMD Am7990
and Am79C90 (CMOS, pin-compatible) LANCE (Local Area Network Controller -
Ethernet) chip set.
In previous releases of NetBSD, the le driver also supported PCnet-PCI
cards based on the AMD 79c970 chipset, which is a single-chip implementa-
tion of an Ethernet interface that has a LANCE compatibility mode com-
bined with a PCI bus interface. PCnet-PCI interfaces have been supported
by the pcn(4) driver since NetBSD 1.6.
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 systems
with large page sizes. The use of trailers is automatically negotiated
with ARP. This negotiation may be disabled, on a per-interface basis,
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, prod-
The A2065 and Ameristar Ethernet cards support only manual media selec-
The Ariadne card supports a software media selection for its two differ-
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).
The ISA-bus Ethernet cards supported by the le interface are:
The EISA-bus Ethernet cards supported by the le interface are:
The MCA-bus Ethernet cards supported by the le interface are:
SKNET Personal MC2
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
The ioasic baseboard devices and the PMAD-AA TURBOchannel option card
provide only an AUI port.
The Sbus Ethernet cards supported by the le interface include:
SCSI and Buffered Ethernet (sun part 501-1860)
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.
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 dis-
tance 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
le%d: transmit buffer error LANCE ran out of buffer before finishing the
transmission of a packet. If this error occurs, the driver software has
le%d: underflow LANCE ran out of buffer before finishing the transmis-
sion 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-
le%d: receiver disabled The LANCE receiver was turned off due to an
le%d: transmitter disabled The LANCE transmitter was turned off due to
arp(4), ifmedia(4), inet(4), intro(4), mca(4), pcn(4), ifconfig(8)
Am79C90 - CMOS Local Area Network Controller for Ethernet, 17881, May
1994, Advanced Micro Devices.
The pmax le driver is derived from a le driver that first appeared in
4.4BSD. Support for multiple bus attachments first appeared in
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
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 comparisons 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.
NetBSD 10.99 June 11, 2022 NetBSD 10.99