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
Controller - 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 systems
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:
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 software 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 failure.
- 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 comparisons for each broadcast packet.
In summary, the cost of the LANCE_REVC_BUG option is:
- loss of multicast support,
and
- 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.