10 Miscellaneous.

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.

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. )

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.

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.

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.

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