Category : Linux Files
Archive   : LINXINFO.ZIP
Filename : COL2.FAQ

Archive-Name: linux/howto/ethernet
Last-Modified: August 28, 1993

Linux Ethernet HOWTO v0.1 -- Last updated August 28, 1993
---------------------------------------------------------------------------
0. Introduction

This is the Ethernet-HOWTO, which is a compilation of information
about which ethernet devices can be used for Linux, and how to
set them up.

This Ethernet-HOWTO is by Donald J. Becker and Paul Gortmaker.
It covers what cards you should and shouldn't buy; how to set
them up, how to run more than one, and other common problems and
questions. It does *not* cover the software end of things, as that
is covered in the NET-2 HOWTO. You can freely distribute this
document as long as you distribute an original copy with the
author's names intact.

Most of this information came from Donald J. Becker
who is responsible for writing and
supporting most of the ethernet drivers that are presently
available. Bj0rn Ekwall is responsible for
the D-Link pocket driver. A special thanks to others who have helped
with the device drivers and testing.

0.1 Disclaimer

This document is *not* gospel. However, it is probably the most
up to date info that you will be able to find. Nobody is responsible
for what happens to your hardware but yourself. If your ethercard
goes up in smoke (...nearly impossible!) we take no responsibility.

0.2 Questions already?

If you have questions about your ethernet card, please READ this
document first. You may also want to join the NET channel of the
Linux-activists mailing list by sending mail to
[email protected]
with the line
X-Mn-Admin: join NET
at the top of the message body (not the subject). Note that the NET
channel is primarily used for discussion of the networking code, and
you may not see much discussion about a particular driver.
Furthermore keep in mind that the NET channel is for development
discussions only. General questions on how to configure your system
should be directed to comp.os.linux.help unless you are actively
involved in the development of part of the networking for Linux.

0.3 Related Documentation

Much of this info came from small files and saved postings by Donald
himself. These can be found in /pub/linux/info on ftp.super.org
[192.31.192.1] Of course, if you are setting up an Ethernet card,
then you will want to read the NET-2 HOWTO so that you can actually
do something with it.

0.4 New versions of this document

New versions of this document can be retrieved via anonymous
FTP from sunsite.unc.edu:/pub/Linux/docs/HOWTO/*. It will also be
posted to the newsgroup comp.os.linux.announce.

0.5 Feedback

Any corrections can be sent to one of us ([email protected]
or [email protected]) We will *attempt* to keep this up to date as
more drivers become available, and as NET-2 matures.

1. Supported Ethernet Cards for Linux

The only thing that one needs to use an ethernet card with Linux
is the appropriate driver. For this, it is essential that the man-
ufacturer will release the technical programming information to
the general public without you (or anyone) having to sign your life
away. A good guide for the likelihood of getting documentation
(or, if you aren't writing code, the likelihood that someone
else will write that driver you really, really need)
is the availability of the Crynwr (nee Clarkson) packet
driver. Given the documentation, you can write a driver for
your card and use it for Linux, at least in theory.

Most cards come with drivers for MS-DOS interfaces such as
NDIS and ODI, but these are useless for Linux. Many people
have suggested directly linking them in or automatic
translation, but this is nearly impossible. The MS-DOS
drivers expect to be in 16 bit mode and hook into "software
interrupts", both incompatible with the Linux kernel. This
incompatibility is actually a feature, as some Linux drivers
are considerably better than their MS-DOS counterparts. The
"8390" series drivers, for instance, use ping-pong transmit
buffers, which are only now being introduced in the MS-DOS world.

Keep in mind that PC ethercards have the widest variety of
interfaces (shared memory, programmed I/O, bus-master, or slave
DMA) of any computer hardware for anything, and supporting a
new ethercard sometimes requires re-thinking most of the
lower-level networking code. Also, similar product numbers
don't always indicate similar products. For instance, the
3c50* product line is wildly different between members.

Here is what drivers are and aren't available.

1.1 3com Ethernet cards

Supported:
3c503, 3c503/16 --
3Com shared-memory ethercards. They also have a
programmed I/O mode that doesn't use the 8390
facilities (their engineers found too many bugs!)
It should be about the same speed as the same bus
width WD80x3, but I don't have a 16 bit version
to benchmark. Unless you are a light user, spend
the extra money and get the 16 bit model, as the
savings aren't huge. The 3c503 does not have "EEPROM
setup", so the diagnostic/setup program isn't needed
before running the card with Linux. The shared memory
address of the 3c503 is set using jumpers that
are shared with the boot PROM address. This is
confusing to people familiar with other ISA cards,
where you always leave the jumper set to "disable"
unless you have a boot PROM. The Linux 3c503 driver
will work with the 3c503 programmed-I/O mode, but this
is slower and less reliable than shared memory mode.

Also, programmed-I/O mode is not tested when updating
the drivers, and the deadman (deadcard?) check code
may be falsely triggered on some machines.
The IRQ line is set in software, with no hints
from e.g. EEPROM. Unlike the MS-DOS driver, the
Linux driver has capability to autoIRQ: it uses the
first available IRQ line in {5,2,3,4}, selected each
time the card is 'ifconfig'ed. (Older driver versions
selected the IRQ at boot time.) The ioctl() call
in 'ifconfig' will return EAGAIN if no IRQ line is
available at that time.

3c509 --
A new card for 3Com. It should be cheap and have
excellent performance. The drawbacks are that it
_requires_ very low interrupt latency, and it isn't
rated for bus speeds greater than 8Mhz. The driver is
written, working, and included in pl12. But it
seems to triggers a Linux TCP bug, so it's not built
as part of the default kernel.

There is also an alpha version of a Linux 3c509
diagnostic and EEPROM setup program, but for now
users that don't like the defaults should use the
MS-DOS EEPROM setup program.

3c579 --
The EISA version of the 509. The current EISA version
uses the same 16 bit wide chip rather than a 32 bit
interface, so the performance increase isn't stunning.
The 3c509 driver should work with the EISA
version, but I have neither an EISA machine nor
a 3c579 to test it on.

Unsupported:

3c501 --
Too brain-damaged to use. Available surplus from many
places. Avoid it like the plague. However, if you are
a bit of a masochist, there is some code in /pub/linux
on ftp.super.org --> look for 3c501.c Again, do not
purchase this card, even as a joke. It's performance
is horrible, and it breaks in many ways.

For those not yet convinced, the 3c501 can only do one
thing at a time -- while you are removing one packet
from the single-packet buffer it cannot receive
another packet, nor can it receive a packet while are
loading a transmit packet. This was fine for a
network between two 8088-based computers where
processing each packet and replying took 10's of
msecs, but modern networks send back-to-back
packets for almost every transaction.

3c505 --
Not available at present.

3c507 --
Not available at present.

1.2 Western Digital / SMC Cards

The ethernet part of Western Digital has been bought by SMC. The
SMC Elite and SMC Elite Plus are the same as late-model WD8003
and WD8013 cards.

Supported:

WD8003, WD8013, SMC Elite, SMC Elite Plus --
A shared memory design by Western Digital. The
8 bit 8003 is slightly less expensive, but only
worth the savings for light use. Over the
years the design has added more registers and an
EEPROM. Clones usually go by the '8013' name, and
usually use a non-EEPROM (jumpered) design. This part
of WD has been sold to SMC, so you'll usually see
something link SMC/WD8013 or SMC Elite Plus (WD8013).
The shared memory makes the cards 10-20% faster,
especially with larger packets. More importantly
(to me at least) it avoids a few bugs in the
programmed-I/O mode of the 8390, allows safe
multi-threaded access to the packet buffer, and
doesn't have a programmed-I/O data register that
hangs your machine during warm-boot probes.

1.3 NExxxx Cards

The prefix "NE" came from Novell Ethernet. Novell followed the
cheapest NatSemi databook design and sold the manufacturing rights
(spun off?) Eagle, just to get reasonably-priced ethercards into
the market.

Supported:

NE1000, NE2000 --
The now-generic name for a bare-bones design around
the NatSemi 8390. They use programmed I/O rather than
shared memory, leading to easier installation but
slightly lower performance and a few problems. Again,
the savings of using an 8 bit NE1000 over the NE2000
are only warranted if you expect light use. Some
recently introduced NE2000 clones use the National
Semiconductor "AT/LANTic" 83905 chip, which offers
a shared memory mode similar to the 8013 and EEPROM
or software configuration. Some problems can arise
with poor clones. See the question and answer section
later in this document, and the section on clones.

NE1500, NE2100 --
The AT1500 driver, recently added to the list of
supported cards, also supports the NE1500, NE2100 and
clones. The driver shipped with pl12 kernel doesn't
detect non-AT1500 cards with autoprobe, but will work
fine if you specify the base address explicitly and
jumper for DMA channel 5.

1.3 Hewlett Packard Cards

HP-LAN ethercards: Nicely made, but hard to find. The model
numbers don't encode anything, so you'll have to go by the
description.

Supported:

272[45]* series, 27245, 27247, 27250 --
They use programmed I/O, similar to the NE*000 boards,
but the data transfer port can be "turned off" when
you aren't accessing it, avoiding problem with
autoprobing drivers. Note that few people seem to use
them, and I've had conflicting reports about changes
between versions with the same model number -- later
versions may not work.

1.4 D-Link

There is a file /usr/src/linux/net/inet/README.DLINK that you
should read if you are going to use D-Link stuff. Note, however
that the installation info in this file is no longer valid, as it
applied to pre NET-2 kernels. It is now a part of the standard kernel.

Supported:

DE-600 --
Laptop users and other folk who might want a quick
way to put their computer onto the ethernet may want
to use this. The driver is included with the default
kernel source tree as of pl12 and possibly earlier.
Bjorn Ekwall wrote the original.
Expect about 80kb/s transfer speed from this via the
parallel port. The file mentioned above contains
a "Known Problems and..." section. I will not repeat
it here. But you should read it. (Hint applied gently
with a sledgehammer.)

DE100, DE200, DE-220-T --
The manual says that it is 100% compatible with the
NE2000. This is not true. You should call them and tell
them you are using their card with Linux, and that they
should correct their documentation. Some pre-0.99pl12
driver versions may have trouble recognizing the DE2**
series as 16 bit cards, and these cards are the most
widely reported as having the spurious transfer address
mismatch errors.

1.5 Cabletron

Yes, another one of these companies that won't release its
programming information. They waited for months before actually
confirming that all their information was proprietary. If you feel
like asking them why they don't want to release their info so that
people can use their cards, write to [email protected]. You should
read section 8.1 of this document, as it has specific information
pertaining to Cabletron.

Supported:

E10**, E10**-x, E20**, E20**-x --
These are NEx000 almost-clones that are reported to work
with the standard NEx000 drivers, thanks to a
ctron-specific check during the probe. If there are
any problems, they are unlikely to be fixed, as the
programming information is unavailable.

Unsupported:

E21** --
Again, there is not much one can do when the
programming information is proprietary. Feel free
to ask [email protected]. This is the only 8390-base
ethercard series that isn't supported by Linux.

1.6 Allied Telesis:

Allied Telesis is the worlds largest maker of separate
transceivers thanks to their low prices, and they now have a
series of low-cost ethercards using the 79C960 version of the AMD
LANCE. These are bus-master cards, and thus probably the fastest
ISA bus ethercards available (although the 3c509 has lower latency
thanks to predictive interrupts). The driver for the AT1500
series is new in the 0.99pl12 kernel, but it won't work
"out-of-the-box" with >16M machines. (NB This isn't a fundamental
limitation, so stop pointing and laughing at the ISA bus. The
driver just needs a hook to allocate low-memory buffers for the
bus-master DMA, and should be just as fast on >16M systems.)

The current (pl12) driver defaults to DMA5. Future driver
versions may figure out a way to autoDMA.

There is a special $20 one-unit-only evaluation offer on the AT1500T
(the TP-only model) until mid-September 1993. The normal list
price is $80-$100.


1.6 Other (less common card supplier) Companies

Arcnet:
There is no Arcnet driver for Linux. Feel free to write a
driver. There might be people with home systems
that will be able to use it with discarded hardware.
With the very low cost and better performance of ethernet,
I expect that most places will be giving away their Arcnet
hardware for free.

An advantage of Arcnet is that all of the cards have identical
interfaces, so once a driver is available it will work for everyone.

Digital / DEC
There is an alpha version of a driver for the early model DEC
DEPCA. DEC is refusing to release information on the later
models. (The rumor is that they don't have enough money to
write and print one!)

Intel:
Not too many of these cards around at present. The Intel Ether-
Express is unsupported at present.

PureData:
The PureData PDUC8028 and PDI8023 series of cards are reported
to work, thanks to special probe code contributed by Mike
Jagdis . The support is integrated
with the WD driver.

Xircom:
Another group that won't release documentation. No cards
supported. Don't look for any support in the future unless
they release their programming information. And this is
highly unlikely, as they *forbid* you from even reverse-
engineering their drivers. Here is some of the results from
people who have tried to deal with Xircom.

"I had no end of problems trying to work with Xircom.
After spending months talking to them and working up a
prospectus, I was told that no information would be forthcoming
and that they were not interested in markets other than the
ISA/DOS market. (I was trying to interface the pocket adapters
to an Amiga). I won't work with them anymore and I won't
recommend their products to anyone."

"They (Xircom) won't give it (programming info.) out. BSDI
was was able to get the spec and write a driver for it, but
only by promising not to give out the source."

Zenith:
The Zenith Z-note is unsupported at present.

2. Clones of popular Ethernet cards.

Due to the popular design of some cards, different companies will
make "clones" or replicas of the original card. However, one must
be careful, as some of these clones are not 100% compatible, and
can be troublesome. Some common problems with "not-quite-clones"
are noted in the question and answer section of this document.

2.1 WD80x3 Clones that are reported to work.

AT-LAN-TEC 8013
PureData (not a 8013 clone, but the 8013 driver has special code)
LANNET LEC-45
PE-8013 (WD-8013 Compatible)

2.2 NE2000 Clones that are reported to work.

Alta Combo NE2000 clone
Aritsoft LANtastic AE-2 (OK, but has flawed error-reporting registers)
Asante Etherpak 2001/2003
AT-LAN-TEC NE2000 clone (uses Winbond chip that traps SCSI drivers)
Cabletron products: E10**, E10**-x, E20**, E20**-x
Cnet UTP 10baseT (NE 2000 emulation)
D-Link Ethernet II (bad clones, but the driver checks for them)
4-Dimension FD0490 EtherBoard16
LTC E-NET/16 P/N: 8300-200-002 ([email protected])
Network Solutions HE-203
SIIG Inc E-Lan/200 (NE 2000 comp.)
SVEC 4 Dimension Ethernet

3 The Card to buy is....

For impatient users that just want a quick, cheap answer the
summary is: get 16 bit thinnet 8013 cards. For more detail as
to the who what where and why, read on.

3.1 Eight bit vs 16 bit.

Unless you are a light user, or are confined to using the smaller
ISA slot, the use of the 8 bit cards like the wd8003 and the 3c503
is really not worth the cost savings. Get the 8013 or the 3c503/16
instead.

3.2 Prices are a bit steep for the XXXX card.

I keep track of the current low-price vendors, just because it's
asked so often. Call AT-LAN-TEC at 301-948-7070. Ask for their
technical support person, "Vincent Bono". As with all purchases,
you should indicate you are buying this for a Linux system.
The last I checked the price for 10 NE2000s was $690, or $69 ea.!
NB Their current NE2000 clone is a model that "traps" other
drivers that probe into their address space.

AT-LAN-TEC also carries a clone, non-EEPROM 8013 board for $89,
and a NE2100 clone. Either is a better choice if the very lowest
price isn't essential.

I've also ordered Alta "Combo" NE2000 cards from Network Express
(aka Main Street Computers) in Fl. A bit more expensive, but
they have bigger ads in Computer Shopper. If you are looking for
prices on your own, try the back of LAN magazine.

Currently (late Aug. '93) there is a market-share war going on in
the ethercard business. Both Allied-Telesis and Accton have
special evaluation deals going on if you call them directly and
reference the right advertisement. (AT1500T $20, max. one, and
Accton NE2000 clone $30+$5s&h, max. 2.)

3.3 Type of cable that your card should support.

Unless you have to conform to an existing network, you will want
to use thinnet or thin ethernet cable. This is the style with the
standard BNC connectors. See the next section on concerns with
different types of ethernet cable.

Most ethercards also come in a "Combo" version for only $10-$20 more.
These have both twisted pair and thinnet transceiver built-in,
allowing you to change your mind later.

4. Cables, Coax, Twisted pairs etc.

If you are starting a network from scratch, it's considerably less
expensive to use thin ethernet, RG58 co-ax cable with BNC connectors,
than old-fashioned thick ethernet, RG-5 cable with N connectors, or
10baseT, twisted pair telco-style cables with RJ-45 "phone"
connectors.

4.1 Thin Ethernet (thinnet).

Thin ethernet is the "ether of choice". The cable is inexpensive. If
you are making your own cables solid-core RG58A is $0.09/ft. and
stranded RG58AU is $0.15/ft. Twist-on BNC connectors are < $2 ea.,
and other misc. pieces are similarly inexpensive. It is essential
that you properly terminate each end of the cable with 50 ohm
terminators, so budget $2 ea. for a pair. It's also vital that
your cable have no "stubs" -- the 'T' connectors must be attached
directly to the ethercards.

4.2 Twisted Pair.

Twisted pair networks require active hubs, which start around $300,
and the raw cable cost can actually be higher than thinnet. They are
usually sold using the claim that you can use your existing telephone
wiring, but it's a rare installation where that turns out to be the
case. The claim that you can upgrade to higher speeds is also
suspect, as most proposed schemes use higher-grade (read $$) cable and
more sophisticated termination ($$$) than you would likely install on
speculation.

4.3 Thick Ethernet.

Thick ethernet is mostly obsolete, and is usually used only to remain
compatible with an existing implementation. You can stretch the rules
and connect short spans of thick and thin ethernet together with a
passive $3 N-to-BNC connector, and that's often the best solution to
expanding an existing thicknet. A correct (but expensive) solution is
to use a repeater in this case.

5 Technical Information.

For those who want to play with the present drivers, or try to make
up their own driver for a card that is presently unsupported, this
information should be useful. If you do not fall into this category,
then perhaps you will want to skip this section.

5.1 Probed Addresses.

While trying to determine what ethernet card is there, the following
addresses are autoprobed, assuming the type and specs of the card
have not been set in the kernel. In /usr/src/linux/net/inet/CONFIG,
one can set the cards that are compiled in to the kernel. As of
0.99pl12, doing a "make config" will ask what cards are to be
supported. The file names below are in /usr/src/linux/net/inet/
----------------------------------------------------------------
wd.c: 0x300, 0x280, 0x380, 0x240
3c503: 0x300, 0x310, 0x330, 0x350, 0x250, 0x280, 0x2a0, 0x2e0
ne.c: 0x300, 0x280, 0x320, 0x340, 0x360
hp.c: 0x300, 0x320, 0x340, 0x280, 0x2C0, 0x200, 0x240
lance.c:0x300, 0x320, 0x340, 0x360
----------------------------------------------------------------
There are some NE2000 clone ethercards out there that are waiting black
holes for autoprobe drivers. While many NE2000 clones are
safe until they are enabled, some can't be reset to a safe mode.
These dangerous ethercards will hang any I/O access to their
"dataports". The typical dangerous locations are:

Ethercard jumpered base Dangerous locations (base + 0x10 - 0x1f)
0x300 * 0x310-0x317
0x320 0x330-0x337
0x340 0x350-0x357
0x360 0x370-0x377

* The 0x300 location is the traditional place to put an ethercard, but
it's also a popular place to put other devices (often SCSI
controllers). The 0x320 location is often the next one chosen, but
that's bad for for the AHA1542 driver probe. The 0x360 location is
bad, because it conflicts with the parallel port at 0x378.

To avoid these lurking ethercard, here are the things you can do:

o Probe for the device's BIOS in memory space. This is easy
and always safe, but it only works for cards that always have
BIOSes, like primary SCSI controllers.

o Avoid probing any of the above locations until you think
you've located your device. The NE2000 clones have a reset range
from +0x18 - +0x1f that will read as 0xff, so probe
there first if possible. It's also safe to probe in the 8390
space at +0x00 - +0x0f, but that area will return
quasi-random values

o If you must probe in the dangerous range, for instance if your
target device has only a few port locations, first check that
there isn't an NE2000 there. You can see how to do this by
looking at the probe code in /usr/src/linux/net/inet/ne.c

5.2 Skeleton / Prototype Driver.

OK. So you have decided that you want to write a driver for the
Foobar Ethernet card, as you have the programming information,
and it hasn't been done yet. (...these are the two main require-
ments 😉 You can use the skeleton network driver that is provided
with the Linux kernel source tree. It can be found in the file
/usr/src/linux/net/inet/README.DRIVERS as of 0.99pl12, and later.

It's also very useful to look at the Crynwr (nee Clarkson) driver
for your target ethercard, if it's available. Russ Nelson
wrote most of these, and he has been very
helpful with his code reviews of the current Linux drivers.

5.3 Driver Interface to the Kernel

Here are some notes that may help when trying to figure out what
the code in the driver segments is doing, or perhaps what it is
supposed to be doing.

-----------------------------------------------------

int ethif_init(struct device *dev)
{
...
dev->send_packet = &ei_send_packet;
dev->open = &ei_open;
dev->stop = &ei_close;
dev->hard_start_xmit = &ei_start_xmit;
...
}

int ethif_init(struct device *dev)

This function is put into the device structure in Space.c. It is
called only at boot time, and returns '0' iff the ethercard 'dev'
exists.

-----------------------------------------------------

static int ei_open(struct device *dev)
static int ei_close(struct device *dev)

This routine opens and initializes the board in response to an
socket ioctl() usually called by 'config' or 'ifconfig'. It is
commonly stuffed into the 'struct device' by ethif_init().

The inverse routine is ei_close(), which should shut down the
ethercard, free the IRQs and DMA channels if the hardware permits,
and turn off anything that will save power (like the transceiver).

(Note: As of NET-2, the relevant program is '/etc/ifconfig' - and
the device *can* be turned off or on via passing 'up' or 'down'
to 'ifconfig' from the command line with the device name.)

-----------------------------------------------------

static int ei_start_xmit(struct sk_buff *skb, struct device *dev)
dev->hard_start_xmit = &ei_start_xmit;

This routine puts packets to be transmitted into the hardware. It
is usually stuffed into the 'struct device' by ethif_init().

When the hardware can't accept additional packets it should set
the dev->tbusy flag. When additional room is available, usually
during a transmit-complete interrupt, dev->tbusy should be cleared
and the higher levels informed with mark_bh(INET_BH).
[[Note: pre0.99.4 kernels didn't use this interface for all packets.]]

-----------------------------------------------------

...
if (dev_rint(buffer, length, is_skb ? IN_SKBUFF : 0, dev))
stats->rx_dropped++;
...
A received packet is passed to the higher levels using dev_rint().
If the unadorned packet data in a memory buffer, dev_rint will copy
it into a 'skbuff' for you. Otherwise a new skbuff should be
kmalloc()ed, filled, and passed to dev_rint() with the IN_SKBUFF flag.

-----------------------------------------------------

5.4 Interrupts and Linux
There are two kinds of interrupt handlers in Linux:
fast ones and slow ones. You decide what kind you are installing by
the flags you pass to irqaction(). The fast ones, such as the serial
interrupt handler, run with _all_ interrupts disabled. The normal
interrupt handlers, such as the one for ethercard drivers, runs with
other interrupts enabled.

There is a two-level interrupt structure. The "fast" part handles the
device register, removes the packets, and perhaps sets a flag. After
it is done, and interrupts are re-enabled, the slow part is run if the
flag is set.

The flag between the two parts is set by:
mark_bh(INET_BH);

Usually this flag is set within dev_rint() during a received-packet
interrupt, and set directly by the device driver during a
transmit-complete interrupt.

You might wonder why all interrupt handlers cannot run in
"normal mode" with other interrupts enabled. Ross Biro uses this
scenario to illustrate the problem:
o You get a serial interrupt, and start processing it.
The serial interrupt is now masked.
o You get a network interrupt, and you start transferring
a maximum-sized 1500 byte packet from the card.
o Another character comes in, but this time the interrupts
are masked!

The "fast" interrupt structure solves this problem by allowing
bounded-time interrupt handlers to run without the risk of leaving
their interrupt lines masked by another interrupt request.

There is an additional distinction between fast and slow interrupt
handlers -- the arguments passed to the handler. A "slow" handler is
defined as

static void
handle_interrupt(int reg_ptr)
{
int irq = -(((struct pt_regs *)reg_ptr)->orig_eax+2);
struct device *dev = irq2dev_map[irq];
...

While a fast handler gets the interrupt number directly

static void
handle_fast_interrupt(int irq)
{
...

--------------------------------------------------------------

5.4 Unresolved Questions / Concerns

There may be some benefit from processing packet data as it is
transferred to and from the ethercard, especially with very fast
processors transferring data to a slow ethercard. As I see it this
question has multiple parts:
1) Is there any useful processing power available, perhaps
during the ISA bus recovery period, or while the 8390
remote DMA is preparing for another transfer??
2) Is there any useful but simple work that can be done
between/during each word of the copy, such as calculating
a CRC, or discarding obviously unwanted packets??
3) would the complexity of an interface to do this make future
ethercard drivers impossible??

There should be a better structure than Space.c Drivers should be
able to autoprobe for all installed ethercards rather than just
quitting after finding the first. I've written code to do this,
but the constant promise (threat?) of DDI has prevented me from
making it standard.

A related topic is the problem of driver probes corrupting
unrelated hardware. Even worse is a probe into a dataport that
isn't set up to transfer data, which will freeze the machine. The
common suggestion is a boot-time device registry that records
already-used I/O ports and shared memory.

6 Possible Problems, Questions and Troubleshooting.

This section tries to answer any unresolved questions, and not so
common solutions to common problems.

6.01 Problem with NE2000 Clones -- "DMA address mismatch"

Is the chip a real NatSemi 8390? (DP8390, DP83901, DP83902 or DP83905)?
If not, some clone chips don't correctly implement the transfer
verification register. MS-DOS drivers never do error checking,
so it doesn't matter to them.

Are most of the messages off by a factor of 2?
If so: Are you using the NE2000 in a 16 bit slot?
Is it jumpered to use only 8 bit transfers?
The Linux driver expects a NE2000 to be a 16 bit slot. A NE1000 can
be in either size slot. This problem can also occur with some clones,
notably D-Link 16 bit cards, that don't have the correct ID bytes
in the station address PROM. [[ This should be fixed in pl12.]]

Are you running the bus faster than 8Mhz?
If you can change the speed (faster or slower), see if that
makes a difference. Most NE2000 clones will run at 16Mhz, but
some may not. Changing speed can also mask a noisy bus.

What other devices are on the bus?
If moving the devices around changes the reliability, then you
have a bus noise problem -- just what that error message was
designed to detect. Congratulations, you've probably found the
source of other problems as well.

6.02 Problem with NE2000 Clones -- Machine Hangs during Boot.

Problem: The machine hangs during boot right after the "8390..." or
"WD...." message. Removing the NE2000 fixes the problem.

Solution: Change your NE2000 base address to 0x360 (or 0x340 for
pl12 or later kernels.)

Reason: Your NE2000 clone isn't a good enough clone. An active
NE2000 is a bottomless pit that will trap any driver
autoprobing in its space. The other ethercard drivers take
great pain to reset the NE2000 so that it's safe, but some
clones cannot be reset. Clone chips to watch out for:
Winbond 83C901. Changing the NE2000 to a less-popular
address will move it out of the way of other autoprobes,
allowing your machine to boot.

Problem: The machine hangs during the SCSI probe at boot.

Solution: It's the same problem as above, change the
ethercard's address.

Problem: The machine hangs during the soundcard probe at boot.

Solution: No, that's really during the silent SCSI probe, and it's
the same problem as above.


6.03 Detected Non-existent Ethercard

Problem: A WD80*3 is falsely detected. Removing the sound or
MIDI card eliminates the "detected" message.

Solution: Update your ethercard driver: new versions include an
additional sanity check.

Reason: Some MIDI ports happen to produce the same checksum as a
WD ethercard.

6.04 Error messages from the 80*3

Problem: You get messages such as the following with your 80*3:
eth0: bogus packet size, status = ........
kmalloc called with impossibly large argument (65400)
eth0: Couldn't allocate sk_buff of size 65400
eth0: receiver overrun

Reason: There is a shared memory problem.

Solution: If the problem is sparodic, you have hardware problems.
Typical problems that are easy to fix are board conflicts,
having cache or "shadow ROM" enabled for that region, or
running your bus faster than 8Mhz. There are also a
surprising number of memory failures on ethernet cards,
so run a diagnostic program if you have one for your
ethercard.

If the problem is continual, and you have have to reboot
to fix the problem, record the boot-time probe message
and mail it to [email protected] Take particular note of
the shared memory location.

6.05 Choosing the Interrupt of the 3c503

Problem: The 3c503 picks IRQ n at boot, but this is needed for some
other device which needs IRQ n. (eg. CD ROM driver, etc.)
Can this be fixed without compiling this into the kernel?

Solution: The 3c503 driver probes for a free IRQ line in the order
{5, 9, 3, 4}, and it should pick a line which isn't being
used. The pre-pl12 (SLS 1.02) driver picked the IRQ line
at boot-time, and the current driver (pl12) chooses when
the card is open()/'ifconfig'ed.

Alternately, you can fix the IRQ at boot by passing
parameters via LILO. The following selects IRQ9, base
location 0x300, , and if_port #1 (the
external transceiver).
lilo: linux ether=9,0x300,0,1,eth0

The following selects IRQ3, probes for the base location,
, and the default if_port #0 (the internal
transceiver)
lilo: linux ether=3,0,0,0,eth0

6.06 Choosing the Output of the 3c503 (thicknet vs. thinnet)

Problem: The supplied 3c503 drivers don't use the AUI (thicknet) port.
How does one choose it over the default thinnet port?

Solution: The 3c503 AUI port can be selected at boot-time with 0.99pl12
and later. The selection is overloaded onto the low bit of
the currently-unused dev->rmem_start variable, so a boot-time
parameter of:
lilo: linux ether=0,0,0,1,eth0
should work. A boot line to force IRQ 5, port base 0x300,
and use an external transceiver is:
lilo: linux ether=5,0x300,0,1,eth0

6.07 Using More than one Ethernet Card. (eg. a gateway machine.)

Problem: What needs to be done so that Linux can run two
ethernet cards?

Solution: Add another entry to Space.c, naming it "eth1" instead
of "eth0". If you want routing to work well you should
use a recent kernel, say 0.99pl11 or later. You may also
want to verify that your driver writer kept all of the
per-card variables in 'dev->priv'. Most do, but the pl12
AT1500/LANCE driver has a single static low-memory buffer.

7 Networking with a Laptop Computer
There are currently only a few ways to put your laptop on a network.
You can use the NET-2 SLIP code (and run at serial line speeds);
you can buy one of the few laptops that come with a NE2000-compatible
ethercard or PCMCIA slot built-in; you can get a laptop with a
docking station and plug in an ISA ethercard; or you can use a
parallel port Ethernet adapter such as the D-Link DE-600.

7.1 Option 1 -- using SLIP

This is the cheapest solution, but by far the most difficult. Also,
you will not get very high transmission rates. Since SLIP is not
really related to ethernet cards, it will not be discussed further
here. See the NET-2 HOWTO.

7.2 Option 2 -- NE2000 Compatible Card built in or PCMCIA slot and ethercard.

The second solution severely limits your laptop choices and is fairly
expensive. Be sure to read the specifications carefully, you may find
that you will have to buy an additional non-standard transceiver to
actually put the machine on a network.

7.3 Option 3 -- ISA Ethercard in the Docking Station.

I recommend the third solution. Docking stations for laptops typically
cost about $250 and provide two full-size ISA slots, two serial and one
parallel port. Most (all?) docking stations are powered off of the
laptop's batteries, and a few allow adding extra batteries in the
docking station if you use short ISA cards. You can add an inexpensive
ethercard and enjoy full-speed ethernet performance.

7.4 Option 4 -- Pocket / Parallel port Adaptors.

The "pocket" ethernet adaptors may also fit your need.
Until recently they actually costed more than a docking station and
cheap ethercard, and most tie you down with a wall-brick power supply.
The only pocket adaptor driver right now is for the D-Link.
I'm also working on a driver for the AT-LAN-TEC/RealTek pocket adaptor.

Most other companies, especially Xircom, treat the programming
information as a trade secret, so support will likely be slow in
coming.

You can sometimes avoid the wall-brick with the adaptors by buying
or making a cable that draws power from the laptop's keyboard
port.


8 Miscellaneous.

Any other associated stuff that didn't fit in anywhere else gets
dumped here. It may not be relevant, and it may not be of general
interest but it is here anyway.

8.1 The Cabletron Story. (...as related by Donald J. Becker)

This is a rather funny story, albeit true. -- Enjoy! P.G.

I contacted Cabletron in early December 1992 for
programming information 11, 1992 (I had called and sent
several earlier messages). I was referred through several
different people, and each one took several days to
respond before they forwarded me to the next. Eventually
I was told I should deal with their (outside?) developer
Mr. Dev.Null. I persisted, and around March it seemed
that I had finally succeed: Cabletron offered to send me
an evaluation board (unrequested) and everything I needed
to use it (what I wanted). The hardware showed up right
away, and I waited, expecting the the programming
information information as well. About a month later I
contacted them, and they told me that "all I needed to use
it" was the standard MS-DOS NDIS drivers, a binary on
standard driver disk. The disk envelope was covered in
legalese, including no-disassembly, no-reverse-engineering
clauses. It was May (and a few email exchanges later)
before I figured out that I had been "slow rolled", and
had wasted about 20 hours on this particular windmill.

The story isn't over yet. People have written to me say
they have vetoed several medium-sized purchases from
Cabletron based on the lack of Linux drivers. Cabletron
must have noticed this because yesterday I got a call
_from_ Cabletron (the first!) stating that they will be
independently writing a Linux driver. Of course, their
lawyers probably haven't read the GPL yet...



----------- end of Ethernet HOWTO ------------


--
Send submissions for comp.os.linux.announce to: [email protected]
: Your NE2000 clone isn't a good enough clone. An active
NE2000 is a bottomless pit