🚀 go-pugleaf

Archive-Name: linux/howto/ethernet/part3
Last-modified: 29 Apr 95


---This is part 3/3---

  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
  transciever 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 final versions of	1.1, but some of them
  didn't have the entry	in `config.in'.	If you have the	file hp-plus.c
  in  /linux/drivers/net/ but no entry in config.in, then add the
  following line under the `HP PCLAN support' line:


	  bool 'HP PCLAN Plus support' CONFIG_HPLAN_PLUS n



  Kernels up tp	1.1.54 are missing the line in `config.in' still.  Do a
  `make	mrproper;make config;make dep;make zlilo' 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.  Token	Ring

  Is there token ring support for Linux?

  To support token ring	requires more than only	a 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-1.1.49.gz



  9.7.3.  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...


  9.7.4.  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?)'


  9.7.5.  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.


  9.7.6.  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.


  9.7.7.  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.


  9.7.8.  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.


  9.7.9.  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.


  9.7.10.  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.


  9.7.11.  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 exmaple, 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 usually
  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