🚀 go-pugleaf

Archive-Name: linux/howto/ethernet/part3
Last-modified: 2 Oct 95

-----BEGIN PGP SIGNED MESSAGE-----

*** The Linux Ethernet HOWTO is posted automatically by the Linux
*** HOWTO coordinator, Greg Hankins <gregh@sunsite.unc.edu>.  Please
*** direct any comments or questions about this HOWTO to the author,
*** Paul Gortmaker <Paul.Gortmaker@anu.edu.au>.

- --- BEGIN Linux Ethernet HOWTO part 3/3 ---

  Try and determine exactly what hardware you have (ie. card
  manufacturer, PCMCIA chip controller manufacturer) and then ask on the
  LAPTOPS channel. Regardless, don't expect things to be all that
  simple.  Expect to have to fiddle around a bit, and patch kernels,
  etc.  Maybe someday you will be able to type `make config' 8-)

  At present, the two PCMCIA chipsets that are supported are the
  Databook TCIC/2 and the intel i82365.

  There is a number of programs on tsx-11.mit.edu in
  /pub/linux/packages/laptops/ that you may find useful. These range
  from PCMCIA Ethercard drivers to programs that communicate with the
  PCMCIA controller chip. Note that these drivers are usually tied to a
  specific PCMCIA chip (ie. the intel 82365 or the TCIC/2)

  For NE2000 compatible cards, some people have had success with just
  configuring the card under DOS, and then booting linux from the DOS
  command prompt via loadlin.

  For those that are net-surfing you can try:

  Don's PCMCIA Stuff <http://cesdis.gsfc.nasa.gov/linux/pcmcia.html>

  Anyway, the PCMCIA driver problem isn't specific to the Linux world.
  It's been a real disaster in the MS-DOS world. In that world people
  expect the hardware to work if they just follow the manual.  They
  might not expect it to interoperate with any other hardware or
  software, or operate optimally, but they do expect that the software
  shipped with the product will function. Many PCMCIA adaptors don't
  even pass this test.

  Things are looking up for Linux users that want PCMCIA support, as
  substantial progress is being made. Pioneering this effort is David
  Hinds. His latest PCMCIA support package can be obtained from cb-
  iris.stanford.edu in the directory /pub/pcmcia/. Look for a file like
  pcmcia-cs-X.Y.Z.tgz where X.Y.Z will be the latest version number.
  This is most likely uploaded to tsx-11.mit.edu as well.

  Note that Donald's PCMCIA enabler works as a user-level process, and
  David Hinds' is a kernel-level solution.  You may be best served by
  David's package as it is much more widely used.


  8.4.  ISA Ethercard in the Docking Station.


  Docking stations for laptops typically cost about $250 and provide two
  full-size ISA slots, two serial and one parallel port. Most 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.


  8.5.  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.  At present, you
  can choose from the D-Link, or the RealTek adaptor.  Most other
  companies, especially Xircom, (see ``Xircom'') treat the programming
  information as a trade secret, so support will likely be slow in
  coming. (if ever!)

  Note that the transfer speed will not be all that great (perhaps
  100kB/s tops?) due to the limitations of the parallel port interface.

  See ``DE-600 / DE-620'' and ``RealTek'' for supported pocket adaptors.

  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. (See
  ``keyboard power'')


  9.  Frequently Asked Questions


  Here are some of the more frequently asked questions about using Linux
  with an Ethernet connection. Some of the more specific questions are
  sorted on a `per manufacturer basis'.  However, since this document is
  basically `old' by the time you get it, any `new' problems will not
  appear here instantly. For these, I suggest that you make efficient
  use of your newsreader. For example, nn users would type


       nn -xX -s'3c'


  to get all the news articles in your subscribed list that have `3c' in
  the subject. (ie. 3com, 3c509, 3c503, etc.)  The moral: Read the man
  page for your newsreader.





  9.1.  Alpha Drivers -- Getting and Using them


  I heard that there is an alpha driver available for my card.  Where
  can I get it?

  The newest of the `new' drivers can be found on Donald's new ftp site:
  cesdis.gsfc.nasa.gov in the /pub/linux/ area. Things change here quite
  frequently, so just look around for it.  There is still all the stuff
  on the old ftp site ftp.super.org in /pub/linux, but this is not being
  actively maintained, and hence will be of limited value to most
  people.

  As of recent v1.1 kernels, the `useable' alpha drivers have been
  included in the standard kernel source tree. When running make config
  you will be asked if you want to be offered ALPHA test drivers.

  Now, if it really is an alpha, or pre-alpha driver, then please treat
  it as such. In other words, don't complain because you can't figure
  out what to do with it. If you can't figure out how to install it,
  then you probably shouldn't be testing it.  Also, if it brings your
  machine down, don't complain. Instead, send us a well documented bug
  report, or even better, a patch!

  People reading this while net-surfing may want to check out:

  Don's Linux Home Page
  <http://cesdis.gsfc.nasa.gov/pub/linux/linux.html>

  for the latest dirt on what is new and upcoming.


  9.2.  Using More than one Ethernet Card per Machine


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

  The hooks for multiple ethercards are all there.  However, note that
  only one ethercard is auto-probed for by default.  This avoids a lot
  of possible boot time hangs caused by probing sensitive cards.

  There are two ways that you can enable auto-probing for the second
  (and third, and...) card. The easiest method is to pass boot-time
  arguments to the kernel, which is usually done by LILO.Probing for the
  second card can be achieved by using a boot-time argument as simple as
  ether=0,0,eth1. In this case eth0 and eth1 will be assigned in the
  order that the cards are found at boot.  Say if you want the card at
  0x300 to be eth0 and the card at 0x280 to be eth1 then you could use


       LILO: linux ether=5,0x300,eth0 ether=15,0x280,eth1


  The ether= command accepts more than the IRQ + i/o + name shown above.
  Please have a look at ``Passing Ethernet Arguments...''  for the full
  syntax, card specific parameters, and LILO tips.

  These boot time arguments can be made permanent so that you don't have
  to re-enter them every time. See the LILO configuration option
  `append' in the LILO manual.

  The second way (not recommended) is to edit the file Space.c and
  replace the 0xffe0 entry for the i/o address with a zero. The 0xffe0
  entry tells it not to probe for that device -- replacing it with a
  zero will enable autoprobing for that device.  If you really need more
  than four ethernet cards in one machine, then you can clone the eth3
  entry and change eth3 to eth4.

  Note that if you are intending to use Linux as a gateway between two
  networks, you will have to re-compile a kernel with IP forwarding
  enabled. Usually using an old AT/286 with something like the `kbridge'
  software is a better solution.

  If you are viewing this while net-surfing, you may wish to look at a
  mini-howto Donald has on his WWW site. Check out Multiple Ethercards
  <http://cesdis.gsfc.nasa.gov/linux/misc/multicard.html>.


  9.3.  Problems with NE1000 / NE2000 cards (and clones)


  Problem: NE*000 ethercard at 0x360 doesn't get detected anymore.

  Reason: Recent kernels ( > 1.1.7X) have more sanity checks with
  respect to overlapping i/o regions. Your NE2000 card is 0x20 wide in
  i/o space, which makes it hit the parallel port at 0x378.  Other
  devices that could be there are the second floppy controller (if
  equipped) at 0x370 and the secondary IDE controller at 0x376--0x377.
  If the port(s) are already registered by another driver, the kernel
  will not let the probe happen.

  Solution: Either move your card to an address like 0x280, 0x340, 0x320
  or compile without parallel printer support.

  Problem: Network `goes away' every time I print something (NE2000)

  Reason: Same problem as above, but you have an older kernel that
  doesn't check for overlapping i/o regions. Use the same fix as above,
  and get a new kernel while you are at it.

  Problem: NE*000 ethercard probe at 0xNNN: 00 00 C5 ... not found.
  (invalid signature yy zz)

  Reason: First off, do you have a NE1000 or NE2000 card at the addr.
  0xNNN?  And if so, does the hardware address reported look like a
  valid one? If so, then you have a poor NE*000 clone. All NE*000 clones
  are supposed to have the value 0x57 in bytes 14 and 15 of the SA PROM
  on the card. Yours doesn't -- it has `yy zz' instead.

  Solution: The driver (/usr/src/linux/drivers/net/ne.c) has a "Hall of
  Shame" list at about line 42. This list is used to detect poor clones.
  For example, the DFI cards use `DFI' in the first 3 bytes of the prom,
  instead of using 0x57 in bytes 14 and 15, like they are supposed to.

  You can determine what the first 3 bytes of your card PROM are by
  adding a line like:


      printk("PROM prefix: %#2x %#2x %#2x\n",SA_prom[0],SA_prom[1],SA_prom[2]);



  into the driver, right after the error message you got above, and just
  before the "return ENXIO" at line 227.

  Reboot with this change in place, and after the detection fails, you
  will get the three bytes from the PROM like the DFI example above.
  Then you can add your card to the bad_clone_list[] at about line 43.
  Say the above line printed out:



  PROM prefix: 0x3F 0x2D 0x1C


  after you rebooted. And say that the 8 bit version of your card was
  called the "FOO-1k" and the 16 bit version the "FOO-2k". Then you
  would add the following line to the bad_clone_list[]:


       {"FOO-1k", "FOO-2k", {0x3F, 0x2D, 0x1C,}},


  Note that the 2 name strings you add can be anything -- they are just
  printed at boot, and not matched against anything on the card.  You
  can also take out the "printk()" that you added above, if you want.
  It shouldn't hit that line anymore anyway. Then recompile once more,
  and your card should be detected.

  Problem: Errors like 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 in 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.

  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.

  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 0x340. Alternatively, you
  can use the device registrar implemented in 0.99pl13 and 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.

  Reason: It's the same problem as above, change the ethercard's
  address, or use the device registrar.

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

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

  Problem: Errors like eth0: DMAing conflict in ne_block_input

  This bug came from timer-based packet retransmissions. If you got a
  timer tick _during_ a ethercard RX interrupt, and timer tick tried to
  retransmit a timed-out packet, you could get a conflict. Because of
  the design of the NE2000 you would have the machine hang (exactly the
  same the NE2000-clone boot hangs).

  Early versions of the driver disabled interrupts for a long time, and
  didn't have this problem. Later versions are fixed. (ie. kernels after
  0.99p9 should be OK.)

  Problem: NE2000 not detected at boot - no boot messages at all

  Donald writes: `A few people have reported a problem with detecting
  the Accton NE2000.  This problem occurs only at boot-time, and the
  card is later detected at run-time by the identical code my (alpha-
  test) ne2k diagnostic program. Accton has been very responsive, but I
  still haven't tracked down what is going on. I've been unable to
  reproduce this problem with the Accton cards we purchased. If you are
  having this problem, please send me an immediate bug report. For that
  matter, if you have an Accton card send me a success report, including
  the type of the motherboard. I'm especially interested in finding out
  if this problem moves with the particular ethercard, or stays with the
  motherboard.'

  Here are some things to try, as they have fixed it for some people:


  o  Change the bus speed, or just move the card to a different slot.

  o  Change the `I/O recovery time' parameter in the BIOS chipset
     configuration.


  9.4.  Problems with WD80*3 cards


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

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

  Solution: Update your ethercard driver: new versions include an
  additional sanity check. If it is the midi chip at 0x388 that is
  getting detected as a WD living at 0x380, then you could also use:

          LILO: linux reserve=0x380,8



  Problem: You get messages such as the following with your 80*3:


       eth0: bogus packet size, status = ........  kmalloc called with impos-
       sibly 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 sporadic, 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
  becker@cesdis.gsfc.nasa.gov - Take particular note of the shared
  memory location.

  Problem: WD80*3 will not get detected at boot.

  Reason: Earlier versions of the Mitsumi CD-ROM (mcd) driver probe at
  0x300 will succeed if just about anything is that I/O location.  This
  is bad news and needs to be a bit more robust.  Once another driver
  registers that it `owns' an I/O location, other drivers (incl. the
  wd80x3) are `locked out' and can not probe that addr for a card.

  Solution: Recompile a new kernel without any excess drivers that you
  aren't using, including the above mcd driver.  Or try moving your
  ethercard to a new I/O addr. Valid I/O addr. for all the cards are
  listed in ``Probed Addresses'' You can also point the mcd driver off
  in another direction by a boot-time parameter (via LILO) such as:

       mcd=0x200,12


  Problem: Old wd8003 and/or jumper-settable wd8013 always get the IRQ
  wrong.

  Reason: The old wd8003 cards and jumper-settable wd8013 clones don't
  have the EEPROM that the driver can read the IRQ setting from.  If the
  driver can't read the IRQ, then it tries to auto-IRQ to find out what
  it is. And if auto-IRQ returns zero, then the driver just assigns IRQ
  5 for an 8 bit card or IRQ 10 for a 16 bit card.

  Solution: Avoid the auto-IRQ code, and tell the kernel what the IRQ
  that you have jumpered the card to is via a boot time argument.  For
  example, if you are using IRQ 9, using the following should work.


       LILO: linux ether=9,0,eth0



  9.5.  Problems with 3Com cards

  Problem: The 3c503 picks IRQ N, but this is needed for some other
  device which needs IRQ N. (eg. CD ROM driver, modem, 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,
  9/2, 3, 4}, and it should pick a line which isn't being used. Very old
  drivers used to pick the IRQ line at boot-time, and the current driver
  (0.99pl12 and newer) 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, <ignored
  value>, and if_port #1 (the external transceiver).


       LILO: linux ether=9,0x300,0,1,eth0


  The following selects IRQ3, probes for the base location, <ignored
  value>, and the default if_port #0 (the internal transceiver)


       LILO: linux ether=3,0,0,0,eth0


  Problem: 3c503: Configured interrupt number XX is out of range.

  Reason: Whoever built your kernel fixed the ethercard IRQ at XX.  The
  above is truly evil, and worse than that, it is not necessary. The
  3c503 will autoIRQ when it gets ifconfig'ed, and pick one of IRQ{5,
  2/9, 3, 4}.

  Solution: Use LILO as described above, or rebuild the kernel, enabling
  autoIRQ by not specifying the IRQ line.

  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


  Also note that kernel revisions 1.00 to 1.03 had an interesting
  `feature'. They would switch to the AUI port when the internal
  transceiver failed. This is a problem, as it will never switch back if
  for example you momentarily disconnect the cable. Kernel versions 1.04
  and newer only switch if the very first Tx attempt fails.


  9.6.  Problems with Hewlett Packard Cards


  Problem: HP Vectra using built in AMD LANCE chip gets IRQ and DMA
  wrong.

  Solution: The HP Vectra uses a different implementation to the
  standard HP-J2405A. The `lance.c' driver used to always use the value
  in the setup register of an HP Lance implementation.  In the Vectra
  case it's reading an invalid 0xff value. Kernel versions newer than
  about 1.1.50 now handle the Vectra in an appropriate fashion.

  Problem: HP Card is not detected at boot, even though kernel was
  compiled with `HP PCLAN support'.

  Solution: You probably have a HP PCLAN+  -- note the `plus'. Support
  for the PCLAN+ was added to mid/late versions of 1.1.  Recompile a
  (possibly newer) kernel with support for the HP PCLAN+ and you should
  be in business.




  9.7.  FAQs Not Specific to Any Card.



  9.7.1.  ifconfig reports the wrong i/o address for the card.


  No it doesn't. You are just interpreting it incorrectly.  This is not
  a bug, and the numbers reported are correct. It just happens that some
  8390 based cards (wd80x3, smc-ultra, etc) have the actual 8390 chip
  living at an offset from the first assigned i/o port.  Try cd
  /usr/src/linux/drivers/net;grep NIC_OFFSET *.c|more to see what is
  going on. This is the value stored in dev->base_addr, and is what
  ifconfig reports. If you want to see the full range of ports that your
  card uses, then try cat /proc/ioports which will give the numbers you
  expect.


  9.7.2.  Shared Memory ISA cards in PCI Machine


  No shared memory cards of any type will work in a PCI machine unless
  you have the PCI ROM BIOS setup configuration set properly. If you
  can't figure out which settings are applicable then ask your supplier
  or local computer guru.


  9.7.3.  Token Ring

  Is there token ring support for Linux?

  To support token ring requires more than only writing a device driver,
  it also requires writing the source routing routines for token ring.
  It is the source routing that would be the most time comsuming to
  write.

  Alan Cox adds: `It will require (...) changes to the bottom socket
  layer to support 802.2 and 802.2 based TCP/IP. Don't expect anything
  soon.'

  Peter De Schrijver has been spending some time on Token Ring lately,
  and has patches that are available for IBM ISA and MCA token ring
  cards. Don't expect miracles here, as he has just started on this as
  of 1.1.42. You can get the patch from:

  aix13ps2.cc.kuleuven.ac.be:/pub/Linux/TokenRing.patch-1.1.xx.gz

  He says that it is only tested on an MCA 16/4 Megabit Token Ring
  board, but it should work with other Tropic based boards.



  9.7.4.  32 Bit / VLB / PCI Ethernet Cards


  What is the selection for 32 bit ethernet cards?

  There aren't many 32 bit ethercard device drivers because there aren't
  that many 32 bit ethercards.

  There aren't many 32 bit ethercards out there because a 10Mbs network
  doesn't justify spending the 5x price increment for the 32 bit
  interface.  See ``Programmed I/O vs. ...'' as to why having an
  ethercard on an 8MHz ISA bus is really not a bottleneck.


  This might change now that AMD has introduced the 32 bit PCnet-VLB and
  PCnet-PCI chips.  The street price of the Boca PCnet-VLB board should
  be under $70 from a place like CMO (see Computer Shopper).  See ``Boca
  PCI/VLB'' for info on these cards.

  See ``AMD PCnet-32'' for info on the 32 bit versions of the LANCE /
  PCnet-ISA chip.

  The DEC 21040 PCI chip is another option (see ``DEC 21040'') for
  power-users.  The 21140 100Base-? chip could prove interesting as
  well, as it is supposedly driver compatible with the 21040. Should be
  good for uncovering any race-conditions, if nothing else...


  9.7.5.  FDDI

  Is there FDDI support for Linux?

  Donald writes: `No, there is no Linux driver for any FDDI boards.  I
  come from a place with supercomputers, so an external observer might
  think FDDI would be high on my list. But FDDI never delivered end-to-
  end throughput that would justify its cost, and it seems to be a
  nearly abandoned technology now that 100base{X,Anynet} seems imminent.
  (And yes, I know you can now get FDDI boards for <$1K. That seems to
  be a last-ditch effort to get some return on the development
  investment. Where is the next generation of FDDI going to come from?)'


  9.7.6.  Linking 10BaseT without a Hub


  Can I link 10BaseT (RJ45) based systems together without a hub?

  You can link 2 machines easily, but no more than that, without extra
  devices/gizmos. See ``Twisted Pair'' -- it explains how to do it. And
  no, you can't hack together a hub just by crossing a few wires and
  stuff. It's pretty much impossible to do the collision signal right
  without duplicating a hub.


  9.7.7.  SIOCSFFLAGS: Try again


  I get `SIOCSFFLAGS: Try again' when I run `ifconfig' -- Huh?

  Some other device has taken the IRQ that your ethercard is trying to
  use, and so the ethercard can't use the IRQ.  You don't necessairly
  need to reboot to resolve this, as some devices only grab the IRQs
  when they need them and then release them when they are done. Examples
  are some sound cards, serial ports, floppy disk driver, etc. You can
  type cat /proc/interrupts to see which interrupts are presently in
  use. Most of the Linux ethercard drivers only grab the IRQ when they
  are opened for use via `ifconfig'. If you can get the other device to
  `let go' of the required IRQ line, then you should be able to `Try
  again' with ifconfig.


  9.7.8.  Link UNSPEC and HW-addr of 00:00:00:00:00:00


  When I run ifconfig with no arguments, it reports that LINK is UNSPEC
  (instead of 10Mbs Ethernet) and it also says that my hardware address
  is all zeros.

  This is because people are running a newer version of the `ifconfig'
  program than their kernel version. This new version of ifconfig is not
  able to report these properties when used in conjunction with an older
  kernel. You can either upgrade your kernel, `downgrade' ifconfig, or
  simply ignore it. The kernel knows your hardware address, so it really
  doesn't matter if ifconfig can't read it.


  9.7.9.  Huge Number of RX and TX Errors


  When I run ifconfig with no arguments, it reports that I have a huge
  error count in both rec'd and transmitted packets. It all seems to
  work ok -- What is wrong?

  Look again. It says RX packets big number PAUSE errors 0 PAUSE dropped
  0 PAUSE overrun 0.  And the same for the TX column.  Hence the big
  numbers you are seeing are the total number of packets that your
  machine has rec'd and transmitted.  If you still find it confusing,
  try typing cat /proc/net/dev instead.


  9.7.10.  Entries in /dev/ for Ethercards


  I have /dev/eth0 as a link to /dev/xxx. Is this right?

  Contrary to what you have heard, the files in /dev/* are not used.
  You can delete any /dev/wd0, /dev/ne0 and similar entries.


  9.7.11.  Linux and ``trailers''


  Should I disable trailers when I `ifconfig' my ethercard?

  You can't disable trailers, and you shouldn't want to. `Trailers' are
  a hack to avoid data copying in the networking layers. The idea was to
  use a trivial fixed-size header of size `H', put the variable-size
  header info at the end of the packet, and allocate all packets `H'
  bytes before the start of a page. While it was a good idea, it turned
  out to not work well in practice.  If someone suggests the use of
  `-trailers', note that it is the equivalent of sacrificial goats
  blood. It won't do anything to solve the problem, but if problem fixes
  itself then someone can claim deep magical knowledge.


  9.7.12.  Non-existent Apricot NIC is detected


  I get eth0: Apricot 82596 at 0x300, 00 00 00 00 00 00 IRQ 10 and
  apricot.c:v.0.02 19/05/94 when I boot, but I don't have an
  ``Apricot''. And then the card I do have isn't detected.

  A few kernel releases had a version of the Apricot driver which only
  used a simple checksum to detect if an Apricot is present. This would
  mistakenly think that almost everything was an Apricot NIC. It really
  should look at the vendor prefix instead. However there is now a check
  to see if the hardware address is all zeros, so this shouldn't happen.
  Your choices are to move your card off of 0x300 (the only place the
  Apricot driver probes), or better yet, get a new kernel.


  10.  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.


  10.1.  Passing Ethernet Arguments to the Kernel


  Here are two generic kernel commands  that can be passed to the kernel
  at boot time. This can be done with LILO, loadlin, or any other
  booting utility that accepts optional arguments.

  For example, if the command was `blah' and it expected 3 arguments
  (say 123, 456, and 789) then, with LILO, you would use:

  LILO: linux blah=123,456,789

  Note: PCI cards have their i/o and IRQ assigned by the BIOS at boot.
  This means that any boot time arguments for a PCI card's IRQ or i/o
  ports are ignored.


  10.1.1.  The ether command


  In its most generic form, it looks something like this:


       ether=IRQ,BASE_ADDR,PARAM_1,PARAM_2,NAME


  All arguments are optional.  The first non-numeric argument is taken
  as the NAME.

  IRQ: Obvious.  An IRQ value of `0' (usually the default) means to
  autoIRQ.  It's a historical accident that the IRQ setting is first
  rather than the base_addr -- this will be fixed whenever something
  else changes.

  BASE_ADDR: Also obvious.  A value of `0' (usually the default) means
  to probe a card-type-specific address list for an ethercard.

  PARAM_1: It was orginally used as an override value for the memory
  start for a shared-memory ethercard, like the WD80*3.  Some drivers
  use the low four bits of this value to set the debug message level.  0
  -- default, 1-7 -- level 1..7, (7 is maximum verbosity)  8 -- level 0
  (no messages). Also, the LANCE driver uses the low four bits of this
  value to select the DMA channel.  Otherwise it uses auto-DMA.

  PARAM_2: The 3c503 driver uses this to select between the internal and
  external transceivers.  0 -- default/internal, 1 -- AUI external.  The
  Cabletron E21XX card also uses the low 4 bits of PARAM_2 to select the
  output media. Otherwise it detects automatically.

  NAME: Selects the network device the values refer to.  The standard
  kernel uses the names `eth0', `eth1', `eth2' and `eth3' for bus-
  attached ethercards, and `atp0' for the parallel port `pocket'
  ethernet adaptor. The arcnet driver uses `arc0' as its name.  The
  default setting is for a single ethercard to be probed for as `eth0'.
  Multiple cards can only be enabled by explicitly setting up their base
  address using these LILO parameters.  The 1.0 kernel has LANCE-based
  ethercards as a special case.  LILO arguments are ignored, and LANCE
  cards are always assigned `eth<n>' names starting at `eth0'.
  Additional non-LANCE ethercards must be explicitly assigned to
  `eth<n+1>', and the usual `eth0' probe disabled with something like
  `ether=0,-1,eth0'.  ( Yes, this is bug. )


  10.1.2.  The reserve command


  This next lilo command is used just like `ether=' above, ie. it is
  appended to the name of the boot select specified in lilo.conf


       reserve=IO-base,extent{,IO-base,extent...}


  In some machines it may be necessary to prevent device drivers from
  checking for devices (auto-probing) in a specific region. This may be
  because of poorly designed hardware that causes the boot to freeze
  (such as some ethercards), hardware that is mistakenly identified,
  hardware whose state is changed by an earlier probe, or merely
  hardware you don't want the kernel to initialize.

  The reserve boot-time argument addresses this problem by specifying an
  I/O port region that shouldn't be probed. That region is reserved in
  the kernel's port registration table as if a device has already been
  found in that region. Note that this mechanism shouldn't be necessary
  on most machines. Only when there is a problem or special case would
  it be necessary to use this.

  The I/O ports in the specified region are protected against device
  probes. This was put in to be used when some driver was hanging on a
  NE2000, or misidentifying some other device as its own.  A correct
  device driver shouldn't probe a reserved region, unless another boot
  argument explicitly specifies that it do so.  This implies that
  reserve will most often be used with some other boot argument. Hence
  if you specify a reserve region to protect a specific device, you must
  generally specify an explicit probe for that device. Most drivers
  ignore the port registration table if they are given an explicit
  address.

  For example, the boot line


       LILO: linux  reserve=0x300,32  ether=0,0x300,eth0


  keeps all device drivers except the ethercard drivers from probing
  0x300-0x31f.

  As usual with boot-time specifiers there is an 11 parameter limit,
  thus you can only specify 5 reserved regions per reserve keyword.
  Multiple reserve specifiers will work if you have an unusually
  complicated request.


  10.2.  Using the Ethernet Drivers as Modules


  At present, all the modules are put in the subdirectory modules in
  your Linux kernel source tree (usually in the form of symbolic links).
  To actually generate the modules, you have to type make modules after
  you have finished building the kernel proper. Earlier kernels built
  them automatically, which wasn't fair to those compiling on 4MB
  386sx-16 machines.

  If you have an 8390 based card, you will have to insert two modules,
  8390.o and then the module for your card.  You can find out if your
  card uses an 8390 chip by reading the above documentation for your
  card, or by just typing something like grep 8390 my_card_name.c in the
  drivers/net/ directory. If grep finds anything, then your card has an
  8390 (or compatible) chip.
  Once you have figured this out, you can insert the module(s) by typing
  insmod mod_name.o as root. The command lsmod will show you what
  modules are loaded, and rmmod will remove them.

  Once a module is inserted, then you can use it just like normal, and
  give ifconfig commands. If you set up your networking at boot, then
  make sure your /etc/rc* files run the insmod command(s) before getting
  to the ifconfig command.

  Also note that a busy module can't be removed. That means that you
  will have to ifconfig eth0 down  (shut down the ethernet card) before
  you can remove the modules. Also, if you use an 8390 based card, you
  will have to remove the card module before removing the 8390 module,
  as the 8390 module is used by the card module.


  10.3.  Contributors


  Other people who have contributed (directly or indirectly) to the
  Ethernet-Howto are, in alphabetical order:


          Ross Biro               <bir7@leland.stanford.edu>
          Alan Cox                <iialan@www.linux.org.uk>
          David C. Davies         <davies@wanton.enet.dec.com>
          Bjorn Ekwall            <bj0rn@blox.se>
          David Hinds             <dhinds@allegro.stanford.edu>
          Michael Hipp            <mhipp@student.uni-tuebingen.de>
          Mike Jagdis             <jaggy@purplet.demon.co.uk>
          Duke Kamstra            <kamstra@ccmail.west.smc.com>
          Russell Nelson          <nelson@crynwr.com>
          Cameron Spitzer         <camerons@NAD.3Com.com>
          Dave Roberts            <david.roberts@amd.com>
          Glenn Talbott           <gt@hprnd.rose.hp.com>




  Many thanks to the above people, and all the other unmentioned testers
  out there.


  10.4.  Closing


  If you have found any glaring typos, or outdated info in this
  document, please let one of us know. It's getting big, and it is easy
  to overlook stuff.

  Thanks,

  Paul Gortmaker, Paul.Gortmaker@anu.edu.au

  Donald J. Becker, becker@cesdis.gsfc.nasa.gov

- --- END Linux Ethernet HOWTO part 3/3 ---

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