6.4 About Module Parameters

Modules accept parameters that you can specify using modprobe to modify a module's behavior:

# modprobe module_name parameter=value ...

Use spaces to separate multiple parameter/value pairs. Array values are represented by a comma-separated list, for example:

# modprobe foo arrayparm=1,2,3,4

You can also change the values of some parameters for loaded modules and built-in drivers by writing the new value to a file under /sys/module/module_name/parameters, for example:

# echo 0 > /sys/module/ahci/parameters/skip_host_reset

The /etc/modprobe.d directory contains .conf configuration files specify module options, create module aliases, and override the usual behavior of modprobe for modules with special requirements. The /etc/modprobe.conf file that was used with earlier versions of modprobe is also valid if it exists. Entries in the /etc/modprobe.conf and /etc/modprobe.d/*.conf files use the same syntax.

The following are commonly used commands in modprobe configuration files:

alias

Creates an alternate name for a module. The alias can include shell wildcards. For example, create an alias for the sd-mod module:

alias block-major-8-* sd_mod

As a result, a command such as modprobe block-major-8-0 has the same effect as modprobe sd_mod.

blacklist

Ignore a module's internal alias that is displayed by the modinfo command. This command is typically used if the associated hardware is not required, if two or more modules both support the same devices, or if a module invalidly claims to support a device. For example, blacklist the alias for the frame-buffer driver cirrusfb:

blacklist cirrusfb

The /etc/modprobe.d/blacklist.conf file prevents hotplug scripts from loading a module, usually so that a different driver binds the module instead, regardless of which driver happens to be probed first.

install

Runs a shell command instead of loading a module into the kernel. For example, load the module snd-emu10k1-synth instead of snd-emu10k1:

install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 && \
/sbin/modprobe snd-emu10k1-synth
options

Defines options for a module,. For example, define the nohwcrypt and qos options for the b43 module:

options b43 nohwcrypt=1 qos=0
remove

Runs a shell command instead of unloading a module. For example, unmount /proc/fs/nfsd before unloading the nfsd module:

remove nfsd { /bin/umount /proc/fs/nfsd > /dev/null 2>&1 || :; } ; \
/sbin/modprobe -r --first-time --ignore-remove nfsd

For more information, see the modprobe.conf(5) manual page.