dc - DEC/Intel 21140, 21142, 21143, 21145 and clones 10/100
dc* at pci? dev ? function ?
dc* at cardbus? dev ? function ?
dcphy* at mii? phy ?
nsphy* at mii? phy ?
lxtphy* at mii? phy ?
The dc driver provides support for several PCI, MiniPCI, and
Ethernet adapters and embedded controllers based on the following
+o DEC 21140 PCI
+o DEC/Intel 21143 PCI and CardBus
+o Intel 21145 PCI
+o Macronix 98713, 98713A, 98715, 98715A, 98725,
98727, and 98732
+o Davicom DM9100, DM9102, and DM9102A
+o ASIX Electronics AX88140A and AX88141
+o ADMtek AL981 Comet PCI and AN983 Centaur-P PCI
+o ADMtek AN985 Centaur-C CardBus
+o Lite-On 82c168 and 82c169 PNIC
+o Lite-On/Macronix 82c115 PNIC II
+o Xircom X3201-based CardBus
All of these chips have the same general register layout,
format and method of operation. All of the clone chips are
based on the
21143 design with various modifications. (The 21140 is an
of the 21143.) The 21143 itself has support for 10baseT,
BNC, AUI, MII
and symbol media attachments, 10 and 100Mbps speeds in full
or half duplex,
built-in NWAY autonegotiation and wake on LAN. The
21143 also offers
several receive filter programming options including
inverse perfect filtering and hash table filtering.
The 21145 seems
to be 10 MBit/s only and has an additional (unsupported)
Some clone chips duplicate the 21143 fairly closely while
maintain superficial similarities. Some support only MII
Others use different receiver filter programming
least one supports only chained DMA descriptors (most support both
chained descriptors and contiguously allocated fixed size
chips (especially the PNIC) also have peculiar bugs. The dc
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 difficult to provide
a complete list of all supported cards. The following NICs
are known to
work with the dc driver at this time:
+o Digital DE500-BA 10/100 (21143, non-MII)
+o Built-in DE500-BA on DEC Alpha workstations
+o Built-in Ethernet on LinkSys EtherFast 10/100 Instant GigaDrive
+o Kingston KNE100TX (21143, MII)
+o D-Link DFE-570TX (21143, MII, quad port)
+o NDC SOHOware SFA110A (98713A)
+o NDC SOHOware SFA110A Rev B4 (98715AEC-C)
+o SVEC PN102-TX (98713)
+o CNet Pro120A (98715A or 98713A) and CNet Pro120B
+o Compex RL100-TX (98713 or 98713A)
+o LinkSys LNE100TX (PNIC 82c168, 82c169)
+o NetGear FA310-TX Rev. D1, D2 or D3 (PNIC 82c169)
+o Matrox FastNIC 10/100 (PNIC 82c168, 82c169)
+o Kingston KNE110TX (PNIC 82c169)
+o LinkSys LNE100TX v2.0 (PNIC II 82c115)
+o Jaton XpressNet (Davicom DM9102)
+o Alfa Inc GFC2204 (ASIX AX88140A)
+o CNet Pro110B (ASIX AX88140A)
+o LinkSys LNE100TX v4.x (ADMtek AN983 Centaur-P)
+o Xircom CardBus, including RealPort models (Xircom
+o IBM EtherJet 10/100 CardBus (Intel 21143)
+o Accton EN1217 (98715) and EN2242 (ADMtek Centaur)
+o Mototech ME316 (ADMtek Centaur)
+o Conexant LANfinity RS7112 MiniPCI
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 hostname.if(5) file.
Note: the built-in NWAY autonegotiation on the
82c168 chip is horribly broken and is not supported by the
dc driver at this time: the chip will operate
in any speed
or duplex mode, however these must be set manually. The
original 82c168 appears on very early revisions
LinkSys LNE100TX and Matrox FastNIC.
10baseT 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
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
Note that the 100baseTX media type may not be available on
21143 adapters which support 10Mbps media attachments only.
21145 supports 10 MBit/s half-duplex only. For more information on configuring
this device, see ifconfig(8).
dc%d: couldn't map ports/memory A fatal initialization error has occurred.
dc%d: couldn't map interrupt A fatal initialization error
dc%d: watchdog timeout A packet was queued for transmission
and a transmit
command was issued, however 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, or if there is
with the network connection (cable).
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
transmit underrun error while attempting to DMA and transmit
This happens if the host is not able to DMA the packet data
NIC's FIFO fast enough. The driver will dynamically increase the transmit
start threshold so that more data must be DMAed into the
the NIC will start transmitting it onto the wire.
dc%d: TX underrun -- using store and forward mode The device continued
to generate transmit underruns even after all possible
threshold settings had been tried, so the driver programmed
the chip for
store and forward mode. In this mode, the NIC will not begin transmission
until the entire packet has been transferred into its
dc%d: chip is in D3 power state -- setting to D0 This message applies
only to adapters which support power management. Some operating 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 configuring 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
able to configure it correctly. The driver tries to detect
and bring the adapter back to the D0 (full power)
state, but this
may not be enough to return the driver to a fully operational condition.
If you see this message at boot time and the driver fails to
device as a network interface, you will have to perform a
boot to have the device properly configured.
Note that this condition only occurs when warm booting from
system. If you power down your system prior to booting OpenBSD,
the card should be configured correctly.
arp(4), cardbus(4), dcphy(4), ifmedia(4), intro(4),
netintro(4), nsphy(4), pci(4), hostname.if(5), ifconfig(8)
ADMtek AL981 and AL983 data sheets,
ASIX Electronics AX88140A and AX88141 data sheets,
Davicom DM9102 data sheet, http://www.davicom8.com.
Intel 21143 Hardware Reference Manual, http://developer.in-
Macronix 98713/A, 98715/A and 98725 data sheets,
Macronix 98713/A and 98715/A app notes,
The dc device driver first appeared in FreeBSD 4.0. OpenBSD
added in OpenBSD 2.7.
The dc driver was written by Bill Paul
<firstname.lastname@example.org> and ported
to OpenBSD by
Aaron Campbell <email@example.com>.
The Macronix application notes claim that in order to put
the chips in
normal operation, the driver must write a certain magic number 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
transmitter works but the receiver tends to produce many unexplained errors
leading to very poor overall performance. The 98715A
does not exhibit
this problem. All other modes on the 98713A seem to
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. Consequently, autonegotiation
is not currently supported for this chipset: the driver defaults
the NIC to 10baseT half duplex, and it's up to the operator
select a different mode if necessary. (Later cards use an
transceiver to implement NWAY autonegotiation and work correctly.)
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, probably due to
PCI DMA burst transfer errors.
The 82c168 and 82c169 PNIC chips also have a receiver bug
manifests during periods of heavy receive and transmit activity, where
the chip will improperly DMA received frames to the host.
The chips appear
to upload several kilobytes of garbage data along with
frame data, dirtying several RX buffers instead of just the
The dc driver detects this condition and will salvage the
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,
result in the receive filter being incorrectly programmed.
The dc driver
will watch for this condition and requeue the setup frame
until it is
The ADMtek AL981 chip (and possibly the AN983 as well) has
to sometimes wedge on transmit: this appears to happen when
queues a sequence of frames which cause it to wrap from the
end of the
transmit descriptor ring back to the beginning. The dc
to avoid this condition by not queuing any frames past the
end of the
transmit ring during a single invocation of the dc_start()
workaround has a negligible impact on transmit performance.
The mii_tick() function does not currently run for ASIX
cable disconnects and reconnects can go unnoticed. The
AX88141 data sheets indicate that they don't have RX or TX
(the bits are reserved). Therefore, we can't seem to
when the adapter is idle.
The Davicom interfaces require a grossly high PCI latency
timer value to
function properly. This means when a Davicom adapter is
present in the
machine, it is given an unfairly high amount of bandwidth on
the PCI bus,
unnecessarily taking time away from other devices. Therefore, Davicom
network cards are not recommended for use with OpenBSD. Be
motherboards have Davicom interfaces built-in.
OpenBSD 3.6 November 20, 1999
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