1Linux and the 3Com EtherLink III Series Ethercards (driver v1.18c and higher)
2----------------------------------------------------------------------------
3
4This file contains the instructions and caveats for v1.18c and higher versions
5of the 3c509 driver. You should not use the driver without reading this file.
6
7release 1.0
828 February 2002
9Current maintainer (corrections to):
10  David Ruggiero <jdr@farfalle.com>
11
12----------------------------------------------------------------------------
13
14(0) Introduction
15
16The following are notes and information on using the 3Com EtherLink III series
17ethercards in Linux. These cards are commonly known by the most widely-used
18card's 3Com model number, 3c509. They are all 10mb/s ISA-bus cards and shouldn't
19be (but sometimes are) confused with the similarly-numbered PCI-bus "3c905"
20(aka "Vortex" or "Boomerang") series.  Kernel support for the 3c509 family is
21provided by the module 3c509.c, which has code to support all of the following
22models:
23
24  3c509 (original ISA card)
25  3c509B (later revision of the ISA card; supports full-duplex)
26  3c589 (PCMCIA)
27  3c589B (later revision of the 3c589; supports full-duplex)
28  3c529 (MCA)
29  3c579 (EISA)
30
31Large portions of this documentation were heavily borrowed from the guide
32written the original author of the 3c509 driver, Donald Becker. The master
33copy of that document, which contains notes on older versions of the driver,
34currently resides on Scyld web server: http://www.scyld.com/network/3c509.html.
35
36
37(1) Special Driver Features
38
39Overriding card settings
40
41The driver allows boot- or load-time overriding of the card's detected IOADDR,
42IRQ, and transceiver settings, although this capability shouldn't generally be
43needed except to enable full-duplex mode (see below). An example of the syntax
44for LILO parameters for doing this:
45
46    ether=10,0x310,3,0x3c509,eth0
47
48This configures the first found 3c509 card for IRQ 10, base I/O 0x310, and
49transceiver type 3 (10base2). The flag "0x3c509" must be set to avoid conflicts
50with other card types when overriding the I/O address. When the driver is
51loaded as a module, only the IRQ and transceiver setting may be overridden.
52For example, setting two cards to 10base2/IRQ10 and AUI/IRQ11 is done by using
53the xcvr and irq module options:
54
55   options 3c509 xcvr=3,3 irq=10,11
56
57
58(2) Full-duplex mode
59
60The v1.18c driver added support for the 3c509B's full-duplex capabilities.
61In order to enable and successfully use full-duplex mode, three conditions
62must be met:
63
64(a) You must have a Etherlink III card model whose hardware supports full-
65duplex operations. Currently, the only members of the 3c509 family that are
66positively known to support full-duplex are the 3c509B (ISA bus) and 3c589B
67(PCMCIA) cards. Cards without the "B" model designation do *not* support
68full-duplex mode; these include the original 3c509 (no "B"), the original
693c589, the 3c529 (MCA bus), and the 3c579 (EISA bus).
70
71(b) You must be using your card's 10baseT transceiver (i.e., the RJ-45
72connector), not its AUI (thick-net) or 10base2 (thin-net/coax) interfaces.
73AUI and 10base2 network cabling is physically incapable of full-duplex
74operation.
75
76(c) Most importantly, your 3c509B must be connected to a link partner that is
77itself full-duplex capable. This is almost certainly one of two things: a full-
78duplex-capable  Ethernet switch (*not* a hub), or a full-duplex-capable NIC on
79another system that's connected directly to the 3c509B via a crossover cable.
80
81/////Extremely important caution concerning full-duplex mode/////
82Understand that the 3c509B's hardware's full-duplex support is much more
83limited than that provide by more modern network interface cards. Although
84at the physical layer of the network it fully supports full-duplex operation,
85the card was designed before the current Ethernet auto-negotiation (N-way)
86spec was written. This means that the 3c509B family ***cannot and will not
87auto-negotiate a full-duplex connection with its link partner under any
88circumstances, no matter how it is initialized***. If the full-duplex mode
89of the 3c509B is enabled, its link partner will very likely need to be
90independently _forced_ into full-duplex mode as well; otherwise various nasty
91failures will occur - at the very least, you'll see massive numbers of packet
92collisions. This is one of very rare circumstances where disabling auto-
93negotiation and forcing the duplex mode of a network interface card or switch
94would ever be necessary or desirable.
95
96
97(3) Available Transceiver Types
98
99For versions of the driver v1.18c and above, the available transceiver types are:
100
1010  transceiver type from EEPROM config (normally 10baseT); force half-duplex
1021  AUI (thick-net / DB15 connector)
1032  (undefined)
1043  10base2 (thin-net == coax / BNC connector)
1054  10baseT (RJ-45 connector); force half-duplex mode
1068  transceiver type and duplex mode taken from card's EEPROM config settings
10712 10baseT (RJ-45 connector); force full-duplex mode
108
109Prior to driver version 1.18c, only tranceiver codes 0-4 were supported. Note
110that the new transceiver codes 8 and 12 are the *only* ones that will enable
111full-duplex mode, no matter what the card's detected EEPROM settings might be.
112This insured that merely upgrading the driver from an earlier version would
113never automatically enable full-duplex mode in an existing installation;
114it must always be explicitly enabled via one of these code in order to be
115activated.
116
117
118(4a) Interpretation of error messages and common problems
119
120Error Messages
121
122eth0: Infinite loop in interrupt, status 2011.
123These are "mostly harmless" message indicating that the driver had too much
124work during that interrupt cycle. With a status of 0x2011 you are receiving
125packets faster than they can be removed from the card. This should be rare
126or impossible in normal operation. Possible causes of this error report are:
127
128   - a "green" mode enabled that slows the processor down when there is no
129     keyboard activitiy.
130
131   - some other device or device driver hogging the bus or disabling interrupts.
132     Check /proc/interrupts for excessive interrupt counts. The timer tick
133     interrupt should always be incrementing faster than the others.
134
135No received packets
136If a 3c509, 3c562 or 3c589 can successfully transmit packets, but never
137receives packets (as reported by /proc/net/dev or 'ifconfig') you likely
138have an interrupt line problem. Check /proc/interrupts to verify that the
139card is actually generating interrupts. If the interrupt count is not
140increasing you likely have a physical conflict with two devices trying to
141use the same ISA IRQ line. The common conflict is with a sound card on IRQ10
142or IRQ5, and the easiest solution is to move the 3c509 to a different
143interrupt line. If the device is receiving packets but 'ping' doesn't work,
144you have a routing problem.
145
146Tx Carrier Errors Reported in /proc/net/dev
147If an EtherLink III appears to transmit packets, but the "Tx carrier errors"
148field in /proc/net/dev increments as quickly as the Tx packet count, you
149likely have an unterminated network or the incorrect media tranceiver selected.
150
1513c509B card is not detected on machines with an ISA PnP BIOS.
152While the updated driver works with most PnP BIOS programs, it does not work
153with all. This can be fixed by disabling PnP support using the 3Com-supplied
154setup program.
155
1563c509 card is not detected on overclocked machines
157Increase the delay time in id_read_eeprom() from the current value, 500,
158to an absurdly high value, such as 5000.
159
160
161(4b) Decoding Status and Error Messages
162
163The bits in the main status register are:
164
165value 	description
1660x01 	Interrupt latch
1670x02 	Tx overrun, or Rx underrun
1680x04 	Tx complete
1690x08 	Tx FIFO room available
1700x10 	A complete Rx packet has arrived
1710x20 	A Rx packet has started to arrive
1720x40 	The driver has requested an interrupt
1730x80 	Statistics counter nearly full
174
175The bits in the transmit (Tx) status word are:
176
177value 	description
1780x02 	Out-of-window collision.
1790x04 	Status stack overflow (normally impossible).
1800x08 	16 collisions.
1810x10 	Tx underrun (not enough PCI bus bandwidth).
1820x20 	Tx jabber.
1830x40 	Tx interrupt requested.
1840x80 	Status is valid (this should always be set).
185
186
187When a transmit error occurs the driver produces a status message such as
188
189   eth0: Transmit error, Tx status register 82
190
191The two values typically seen here are:
192
1930x82
194Out of window collision. This typically occurs when some other Ethernet
195host is incorrectly set to full duplex on a half duplex network.
196
1970x88
19816 collisions. This typically occurs when the network is exceptionally busy
199or when another host doesn't correctly back off after a collision. If this
200error is mixed with 0x82 errors it is the result of a host incorrectly set
201to full duplex (see above).
202
203Both of these errors are the result of network problems that should be
204corrected. They do not represent driver malfunction.
205
206
207(5) Revision history (this file)
208
20928Feb02 v1.0  DR   New; major portions based on Becker original 3c509 docs
210
211