There does not seem to be a simple tutorial that describes the following files:

/etc/modutils/
/etc/modules.conf
/etc/conf.modules

/etc/modules
/etc/modprobe.d

Most distributions happen to contain all of those files by default. So even though you might never need to use 2.4 kernel, you would still have them. And that simply makes things confusing.

Here is quick run-down of the facts about the module configuration in linux, and how to know which files to use for which major kernel version.

kernel 2.4 uses 'modutils', kernel 2.6 uses 'module-init-tools'

For 2.4:

modutils uses /etc/modules.conf which is built automatically by piecing together files in /etc/modutils/

/etc/conf.modules is old name of what's now /etc/modules.conf for 2.4 and pre-2.4 kernels

For 2.6:

module-init-tools uses all files in /etc/modprobe.d/

/etc/modules lists modules to be loaded at boot time. you can run modconf or simply edit that file by hand.

if /etc/modules-2.6 exists, that will be used instead if your kernel is 2.6

/etc/modprobe.d/ contains configuration for modprobe such as aliases

/etc/modprobe.d/ is mainly intended for kernel auto-loading of modules, so don't mess with it if you don't know what you are doing.

In conclusion:

If you need to add a module to be loaded at boot time then add the module's name to /etc/modules and don't worry about the other files. If you are running 2.6 then all you need is /etc/modules and /etc/modprobe.d/.

If you have any questions about this page, you can reach me at k AT goudkov DOT com.

Konstantin Goudkov,
www.goudkov.com