modprobe.conf, modprobe.d - Configuration file/directory for modprobe

Because the modprobe command can add or remove extra more than one module, due to module dependencies, we need a method of specifying what options are to be used with those modules. /etc/modprobe.conf and all files under the /etc/modprobe.d directory specifies those options, as required. It can also be used to create convenient aliases: alternate names for a module. Finally, it can override the normal modprobe behavior altogether, for those with very special requirements (such as inserting more than one module).

Note that module and alias names (like other module names) can have - or _ in them: both are interchangable throughout all the module commands.

The format of modprobe.conf and files under modprobe.d is simple: one command per line, with blank lines and lines starting with # ignored (useful for adding comments). A \ at the end of a line causes it to continue on the next line, which makes the file a bit neater.

The syntax is a simplification of modules.conf, used in 2.4 kernels and earlier.

alias wildcard modulename

This allows you to give alternate names for a module. For example: "alias my-mod really_long_modulename" means you can use "modprobe my-mod" instead of "modprobe really_long_modulename". You can also use shell-style wildcards, so "alias my-mod* really_long_modulename" means that "modprobe my-mod-something" has the same effect. You can't have aliases to other aliases (that way lies madness), but aliases can have options, which will be added to any other options.

Note that modules can also contain their own aliases, which you can see using modinfo. These aliases are used as a last resort (ie. if there is no real module, install, remove, or alias command in the configuration).

options modulename option...

This command allows you to add options to the module modulename (which might be an alias) every time it is inserted into the kernel: whether directly (using modprobe modulename, or because the module being inserted depends on this module.

All options are added together: they can come from an option for the module itself, for an alias, and on the command line.

install modulename command...

This is the most powerful primitive in modprobe.conf: it tells modprobe to run your command instead of inserting the module in the kernel as normal. The command can be any shell command: this allows you to do any kind of complex processing you might wish. For example, if the module "fred" worked better with the module "barney" already installed (but it didn't depend on it, so modprobe won't automatically load it), you could say "install fred /sbin/modprobe barney; /sbin/modprobe --ignore-install fred", which would do what you wanted. Note the --ignore-install, which stops the second modprobe from re-running the same install command. See also remove below.

You can also use install to make up modules which don't otherwise exist. For example: "install probe-ethernet /sbin/modprobe e100 || /sbin/modprobe eepro100", which will try first the e100 driver, then the eepro100 driver, when you do "modprobe probe-ethernet".

If you use the string "$CMDLINE_OPTS" in the command, it will be replaced by any options specified on the modprobe command line. This can be useful because users expect "modprobe fred opt=1" to pass the "opt=1" arg to the module, even if there's an install command in the configuration file. So our above example becomes "install fred /sbin/modprobe barney; /sbin/modprobe --ignore-install fred $CMDLINE_OPTS"

remove modulename command...

This is similar to the install command above, except it is invoked when "modprobe -r" is run. The removal counterparts to the two examples above would be: "remove fred /sbin/modprobe -r --ignore-remove fred && /sbin/modprobe -r barney", and "remove probe-ethernet /sbin/modprobe -r eepro100 || /sbin/modprobe -r e100".

include filename

Using this command, you can include other configuration files, or whole directories, which is occasionally useful. Note that aliases in the included file will override aliases previously declared in the current file.

blacklist modulename

Modules can contain their own aliases: usually these are aliases describing the devices they support, such as "pci:123...". These "internal" aliases can be overridden by normal "alias" keywords, but there are cases where two or more modules both support the same devices, or a module invalidly claims to support a device: the blacklist keyword indicates that all of a particular module's internal aliases are to be ignored.

There is a generate_modprobe.conf program which should do a reasonable job of generating modprobe.conf from your current (2.4 or 2.2) modules setup.

Although the syntax is similar to the older /etc/modules.conf, there are many features missing. There are two reasons for this: firstly, install and remove commands can do just about anything, and secondly, the module-init-tools modprobe is designed to be simple enough that it can be easily replaced.

With the complexity of actual module insertion reduced to three system calls (open, read, init_module), and the modules.dep file being simple and open, producing a more powerful modprobe variant can be done independently if there is a need.

This manual page Copyright 2004, Rusty Russell, IBM Corporation.

modprobe(8), modules.dep(5)