dc(4)

NAME

dc - DEC/Intel 21143 and clone 10/100 Ethernet driver

SYNOPSIS

To compile this driver into the kernel, place the  following
lines in your
kernel configuration file:
      device miibus
      device dc
Alternatively,  to load the driver as a module at boot time,
place the
following line in loader.conf(5):
      if_dc_load="YES"

DESCRIPTION

The dc driver provides support for several PCI Fast Ethernet
adapters and embedded controllers based on the the DEC/Intel 21143
chipset and clones.
All of supported chipsets have the same general register
layout, DMA descriptor format and method of operation. All of the clone
chips are based on the 21143 design with various modifications. The
21143 itself has support for 10baseT, BNC, AUI, MII and symbol media at
tachments, 10 and 100Mbps speeds in full or half duplex, built in NWAY au
tonegotiation and wake on LAN. The 21143 also offers several receive fil
ter programming options including perfect filtering, inverse perfect
filtering and hash table filtering.
Some clone chips duplicate the 21143 fairly closely while
others only maintain superficial similarities. Some support only MII
media attachments. Others use different receiver filter programming
mechanisms. At least one supports only chained DMA descriptors (most sup
port both chained descriptors and contiguously allocated fixed size
rings). Some chips (especially the PNIC) also have peculiar bugs. The dc
driver does its best to provide generalized support for all of these
chipsets in order to keep special case code to a minimum.
These chips are used by many vendors which makes it diffi
cult to provide a complete list of all supported cards.
The dc driver supports the following media types:
autoselect Enable autoselection of the media type and
options. The: user can manually override the autoselected; mode by
adding media options to the /etc/rc.conf; file.; Note: the built-in NWAY autonegotiation on; the original
PNIC 82c168 chip is horribly broken and is; not supported
by the dc driver at this time (see the BUGS; section for
details). The original 82c168 appears on; very early
revisions of the LinkSys LNE100TX and Ma; trox FastNIC.
10baseT/UTP Set 10Mbps operation. The mediaopt option
can also be: used to enable full-duplex operation. Not; specifying
full-duplex implies half-duplex mode.
100baseTX Set 100Mbps (Fast Ethernet) operation. The
mediaopt: option can also be used to enable; full-duplex operation.
Not specifying full-duplex implies; half-duplex mode.
The dc driver supports the following media options:
full-duplex Force full duplex operation. The interface
will operate: in half duplex mode if this media option is; not specified.
Note that the 100baseTX media type may not be available on
certain Intel 21143 adapters which support 10Mbps media attachments only.
For more information on configuring this device, see ifconfig(8).

HARDWARE

The dc driver provides support for the following chipsets:

+o DEC/Intel 21143
+o ADMtek AL981 Comet, AN985 Centaur, ADM9511 Centaur II
and ADM9513: Centaur II
+o ASIX Electronics AX88140A and AX88141 +o Conexant LANfinity RS7112 (miniPCI) +o Davicom DM9009, DM9100, DM9102 and DM9102A +o Lite-On 82c168 and 82c169 PNIC +o Lite-On/Macronix 82c115 PNIC II +o Macronix 98713, 98713A, 98715, 98715A, 98715AEC-C,
98725, 98727 and: 98732
+o Xircom X3201 (cardbus only)
The following NICs are known to work with the dc driver at
this time:
+o 3Com OfficeConnect 10/100B (ADMtek AN985 Centaur-P) +o Abocom FE2500 +o Accton EN1217 (98715A) +o Accton EN2242 MiniPCI +o Adico AE310TX (98715A) +o Alfa Inc GFC2204 (ASIX AX88140A) +o Built in 10Mbps only Ethernet on Compaq Presario 7900
series desktops: (21143, non-MII)
+o Built in DE500-BA on DEC Alpha workstations (21143, non
MII) +o Built in Sun DMFE 10/100 Mbps Ethernet on Sun Netra X1
and Sun Fire: V100 (DM9102A, MII)
+o Built in Ethernet on LinkSys EtherFast 10/100 Instant
GigaDrive: (DM9102, MII)
+o CNet Pro110B (ASIX AX88140A) +o CNet Pro120A (98715A or 98713A) and CNet Pro120B (98715) +o Compex RL100-TX (98713 or 98713A) +o D-Link DFE-570TX (21143, MII, quad port) +o Digital DE500-BA 10/100 (21143, non-MII) +o ELECOM Laneed LD-CBL/TXA (ADMtek AN985) +o Hawking CB102 CardBus +o IBM EtherJet Cardbus Adapter +o Intel PRO/100 Mobile Cardbus (versions that use the
X3201 chipset) +o Jaton XpressNet (Davicom DM9102) +o Kingston KNE100TX (21143, MII) +o Kingston KNE110TX (PNIC 82c169) +o LinkSys LNE100TX (PNIC 82c168, 82c169) +o LinkSys LNE100TX v2.0 (PNIC II 82c115) +o LinkSys LNE100TX v4.0/4.1 (ADMtek AN985 Centaur-P) +o Matrox FastNIC 10/100 (PNIC 82c168, 82c169) +o Melco LGY-PCI-TXL +o Microsoft MN-120 10/100 CardBus (ADMTek Centaur-C) +o Microsoft MN-130 10/100 PCI (ADMTek Centaur-P) +o NDC SOHOware SFA110A (98713A) +o NDC SOHOware SFA110A Rev B4 (98715AEC-C) +o NetGear FA310-TX Rev. D1, D2 or D3 (PNIC 82c169) +o Netgear FA511 +o PlaneX FNW-3602-T (ADMtek AN985) +o SMC EZ Card 10/100 1233A-TX (ADMtek AN985) +o SVEC PN102-TX (98713) +o Xircom Cardbus Realport +o Xircom Cardbus Ethernet 10/100 +o Xircom Cardbus Ethernet II 10/100

NOTES

On sparc64 the dc driver respects the local-mac-address?
system configuration variable for the built in Sun DMFE 10/100 Mbps Ether
net interfaces on Sun Netra X1 and Sun Fire V100. This system configura
tion variable can be set in the Open Firmware boot monitor using the
setenv command or
by eeprom(8). If set to ``false'' (the default), the dc
driver will use the system's default MAC address for both of the built in
devices. If set to ``true'', the unique MAC address of each interface is
used rather than the system's default MAC address.

DIAGNOSTICS

dc%d: couldn't map ports/memory A fatal initialization er
ror has occurred.
dc%d: couldn't map interrupt A fatal initialization error
has occurred.
dc%d: watchdog timeout A packet was queued for transmission
and a transmit command was issued, but the device failed to acknowledge
the transmission before a timeout expired. This can happen if the
device is unable to deliver interrupts for some reason, of if there is
a problem with the network connection (cable or network equipment)
that results in a loss of link.
dc%d: no memory for rx list The driver failed to allocate
an mbuf for the receiver ring.
dc%d: TX underrun -- increasing TX threshold The device
generated a transmit underrun error while attempting to DMA and transmit
a packet. This happens if the host is not able to DMA the packet data
into the NIC's FIFO fast enough. The driver will dynamically in
crease the transmit start threshold so that more data must be DMAed into the
FIFO before the NIC will start transmitting it onto the wire.
dc%d: TX underrun -- using store and forward mode The de
vice continued to generate transmit underruns even after all possible
transmit start threshold settings had been tried, so the driver programmed
the chip for store and forward mode. In this mode, the NIC will not be
gin transmission until the entire packet has been transfered into its
FIFO memory.
dc%d: chip is in D3 power state -- setting to D0 This mes
sage applies only to adapters which support power management. Some oper
ating systems place the controller in low power mode when shutting down,
and some PCI BIOSes fail to bring the chip out of this state before con
figuring it. The controller loses all of its PCI configuration in the D3
state, so if the BIOS does not set it back to full power mode in time, it
will not be able to configure it correctly. The driver tries to detect
this condition and bring the adapter back to the D0 (full power)
state, but this may not be enough to return the driver to a fully opera
tional condition. If you see this message at boot time and the driver fails to
attach the device as a network interface, you will have to perform a
second warm boot to have the device properly configured.
Note that this condition only occurs when warm booting from
another operating system. If you power down your system prior to boot
ing FreeBSD, the card should be configured correctly.

HISTORY

The dc device driver first appeared in FreeBSD 4.0.

AUTHORS

The dc driver was written by Bill Paul
<wpaul@ee.columbia.edu>.

BUGS

The Macronix application notes claim that in order to put
the chips in normal operation, the driver must write a certain magic num
ber into the CSR16 register. The numbers are documented in the app
notes, but the exact meaning of the bits is not.
The 98713A seems to have a problem with 10Mbps full duplex
mode. The transmitter works but the receiver tends to produce many un
explained errors leading to very poor overall performance. The 98715A
does not exhibit this problem. All other modes on the 98713A seem to
work correctly.
The original 82c168 PNIC chip has built in NWAY support
which is used on certain early LinkSys LNE100TX and Matrox FastNIC cards,
however it is horribly broken and difficult to use reliably. Consequent
ly, autonegotiation is not currently supported for this chipset: the driv
er defaults the NIC to 10baseT half duplex, and it is up to the operator
to manually select a different mode if necessary. (Later cards use an
external MII transceiver to implement NWAY autonegotiation and work cor
rectly.)
The dc driver programs 82c168 and 82c169 PNIC chips to use
the store and forward setting for the transmit start threshold by default.
This is to work around problems with some NIC/PCI bus combinations
where the PNIC can transmit corrupt frames when operating at 100Mbps, prob
ably due to PCI DMA burst transfer errors.
The 82c168 and 82c169 PNIC chips also have a receiver bug
that sometimes manifests during periods of heavy receive and transmit ac
tivity, where the chip will improperly DMA received frames to the host.
The chips appear to upload several kilobytes of garbage data along
with the received frame data, dirtying several RX buffers instead of
just the expected one. The dc driver detects this condition and will
salvage the frame; however, it incurs a serious performance penalty in
the process.
The PNIC chips also sometimes generate a transmit underrun
error when the driver attempts to download the receiver filter setup frame,
which can result in the receive filter being incorrectly programmed.
The dc driver will watch for this condition and requeue the setup frame
until it is transfered successfully.
The ADMtek AL981 chip (and possibly the AN985 as well) has
been observed to sometimes wedge on transmit: this appears to happen when
the driver queues a sequence of frames which cause it to wrap from the
end of the transmit descriptor ring back to the beginning. The dc
driver attempts to avoid this condition by not queuing any frames past the
end of the
transmit ring during a single invocation of the dc_start()
routine. This workaround has a negligible impact on transmit performance.
BSD July 16, 2005

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See also

dc(4)

NAME

SYNOPSIS

DESCRIPTION

HARDWARE

NOTES

DIAGNOSTICS

SEE ALSO

HISTORY

AUTHORS

BUGS