[Appendix D] D.6 Using Loadable Ethernet Drivers

D.6 Using Loadable Ethernet Drivers

Early versions of Linux used a so-called monolithic kernel. At that time, Linux distributions typically included several kernels, offering support for a variety of devices that might be needed to boot and install a Linux system. Devices not needed to boot and install a system - so-called special devices - had second-class status. To access special devices, users had to compile customized kernels that included support for those devices. When a user added a device to a system, it was often necessary to compile a new kernel, which was something of an inconvenience.

More recent versions of Linux feature a modular kernel, which allows drivers to be dynamically loaded on command. This makes it much easier than before to configure your Linux system to support Ethernet cards and other special devices. Debian GNU/Linux is generally able to configure your primary Ethernet card automatically, by probing for it during installation of Linux.

However, the autoprobe doesn't always succeed. Moreover, if you have more than one Ethernet card, the installation program sets up only the first card it finds. To set up additional cards, you need to know a bit about Linux's loadable modules.

D.6.1 Dynamically Loading a Modular Driver

To dynamically load a modular driver, you issue the following command:

 insmod  driver

Where driver specifies the module to be loaded. Table D.9 lists modular Ethernet drivers and the cards they support. As an example, the command:

 insmod ne2k-pci

loads the modular driver for the PCI-based NE2000 Ethernet card.

Table D.9: Modular Ethernet Drivers and Supported Cards
Driver	Cards
`3c501`	3Com 3c501
`3c503`	3Com EtherLink II
`3c505`	3Com EtherLink Plus
`3c507`	3Com EtnerLink 16
`3c509`	3Com EtherLink III
`3c515`	3Com EtherLink XL
`8390`	National Semiconductor NS8390
`a2065`	Commodore/Ameristar A2065
`ac3200`	Ansel Communications AC3200 (EISA)
`apricot`	Apricot 82596
`arcnet`	ARCnet COM9026 and COM20020
`ariadne`	Village Tronic Ariadne
`at1700`	Allied Telesis AT1700
`atari_bionet`	Atari BIONET-100
`atari_pamsnet`	Atari PAMsNet
`atarilance`	Atari VME Lance
`cops`	LocalTalk PC
`de4x5`	EtherWORKS DE425, DE434, DE435, DE450, DE500, DC21040, DC21041, DC21142, DC21143
`de600`	D-Link DE-600
`de620`	D-Link DE-620
`depca`	DEPCA/EtherWORKS DEPCA, DE100, DE101, DE200, DE201, DE202, DE210, DE422
`dgrs`	Digi RightSwitch SE-X
`e2100`	Cabletron E2100
`eepro`	Intel EtherExpress Pro/10
`eepro100`	Intel EtherExpress Pro/100
`eexpress`	Intel EtherExpress
`epic100`	SMC 83c170 EPIC/100
`eth16i`	ICL EtherTeam 16i, EtherTeam 32 (EISA)
`ewrk3`	EtherWORKS DE203, DE204, DE205
`hp-plus`	HP PCLAN/Plus
`hp`	HP LAN
`hp100`	HP J2585A, J2585B, J2970, J2973, J2573Compex ReadyLink ENET100-VG4Compex FreedomLine 100/VG
`hydra`	Hydra Amiganet
`ibmtr`	IBM token ring
`lance`	Allied Telesis AT1500HP J2405ANE 2100, 2500
`ne`	NE1000, NE2000 (non-PCI)
`ne2k-pci`	NE2000 (PCI)
`ni52`	Rascal-Interlan NI5210
`ni65`	Rascal-Interlan NI6510
`pcnet`	AMD PCnet32- and PCnetPCI-based cards
`rt18139`	Cards based on the RTL8129 and RTL8139 PCI Ethernet chips, such as: ALFA GFC2206 Allied Telesyn AT2550 Genius GF100TXR (RTL8139) NDC Communications NE100TX-E SiS 900 (PCI) SMC 1211TX (PCI)
`smc-ultra`	SMC Ultra, UltraEZ, Ultra32
`smc9194`	SMC 9000
`tlan`	Various Compaq and Olicom cards
`tulip`	Cards based on the DEC 21040/21041/21140/21142/21143, such as: Accton EtherDuo PCI, EN1207 Adaptec ANA6901/C, ANA6911/TX C-NET CNE-935 Cogent EM100, EM110, EM400, EM960, EM964 Quartet Danpex EN-9400P3 D-Link DFE500-Tx, DE-530CT, DFE-540TX Linksys EtherPCI Kingston EtherX KNT40T, EtherX KNE100TX Netgear FX310 TX 10/100 SMC EtherPower, 8432BT, EtherPower10/100, EtherPower10/100 Surecom EP-320X
`tulip` (cont.)	Thomas Conrad TC5048 Znyx ZX312 EtherAction, ZX314, ZX315 EtherArray, ZX342, ZX344, ZX345, ZX346, ZX348, ZX351
`wavelan`	AT&T/NCR GIS WaveLAN
`wd`	WD8003, WD8013
`yellowfin`	Packet Engines G-NIC

When a driver is loaded, it generally probes to locate the supported device. In case an autoprobe fails, most drivers let you specify the I/O port and IRQ by using a command like the following:

 insmod ne2k=pci io=0x280 irq=11

Some cards support additional options; these are documented in the file /usr/src/linux/Documentation/networking/net-modules.txt.

D.6.2 Loading Modular Drivers at Boot Time

The Linux kernel automatically loads modules specified in the module configuration file, /etc/conf.modules. So, once you've determined the proper module and options required by your Ethernet card, you can add a line or two to the module configuration file so that your card will be made ready to operate each time you boot your system.

The alias directive associates a logical module name with an actual module. Logical module names specify types of devices; for example, eth0 specifies the first Ethernet card in a system and eth1 specifies the second Ethernet card in a system. Suppose your system includes two Ethernet cards: a non-PCI-based NE2000 and an SMC EtherPower, which is based on DEC's TULIP chip. You could use the following directives to automatically load these modules at boot time:

 alias eth0 ne alias eth1 tulip

If a driver requires options, you can specify them by using an options directive, which has the following form:

 options  driver argument= value[, value,...]              argument= value[, value,...] ...

For example, you might specify the I/O port and IRQ used by the NE2000 card like this:

 options ne io=0x280 irq=12

Most ISA modules accept parameters like io=0x340 and irq=12 on the insmod command line. You should supply these parameters to avoid probing for the card. Unlike PCI and EISA devices, ISA devices sometimes cannot be safely auto-probed.

D.6.3 Administering Modular Drivers

The lsmod command, which takes no arguments, lists the loaded modular drivers. To unload a modular driver, specify the driver as the argument of the rmmod command. For example, to remove the ne driver, issue the command:

 rmmod ne

By specifying the -a argument, you can cause rmmod to unload every unused module; that is, every module not associated with an operational device:

 rmmod -a

You can't remove a module that's in use; therefore, you must shut down the device before removing it. To shut down an Ethernet device, you can use linuxconfig. Or, you can issue the following command:

 ifconfig eth n down

where eth n specifies the logical device (for example, eth0 or eth1).