Linux device drivers come in the form of kernel modules - object files which may be loaded into the running kernel to extend its functionality. The list of currently loaded kernel modules can be obtained using the lsmod command, modules may be loaded using modprobe, and removed using modprobe -r. The depmod command may be used to regenerate the list of available modules (after installation of the new modules, for example), even though it is pretty unlikely that you will ever need to invoke it by hand.
Normally, the devices are detected and necessary kernel modules are loaded by udev during boot time. Occasionally, one may need finer control over the loading of kernel modules, for example to pass the additional parameters to the module, force loading of some modules on startup, or prevent certain module(s) from being loaded.
If some modules are not loaded automatically by udev, but
you would like them to be loaded during boot, it is possible to force it by
listing the names of the modules in
/etc/modules. This will
be scanned for the names of the modules (one name per line), which will then be
loaded using modprobe. For example, a typical
/etc/modules might look like:
To find out what parameters are accepted by a given module, you can use the modinfo command, for example:
filename: /lib/modules/3.2.0-2-686-pae/kernel/drivers/block/loop.ko alias: devname:loop-control alias: char-major-10-237 alias: block-major-7-* license: GPL depends: intree: Y vermagic: 3.2.0-2-686-pae SMP mod_unload modversions 686 parm: max_loop:Maximum number of loop devices (int) parm: max_part:Maximum number of partitions per loop device (int)
To add custom arguments to the modules loaded by udev early
in the boot process, you need to create a custom configuration file for
modprobe, which udev uses to load the
modules. For example, to pass an
libata kernel module, create
/etc/modprobe.d/local.conf file with the following line:
options libata atapi_enabled=1
You can use any name ending in
.conf for the
configuration files in
/etc/modprobe.d and put
options lines in the same file.
Sometimes two different modules claim support for the same device, usually
because two slightly different versions of the device exist, requiring
different kernel modules to operate. In such situation udev
loads both kernel modules, with unpredictable results. To avoid this problem,
you can prevent any module (let's say,
tulip) from loading
by creating a file containing the line:
/etc/modprobe.d directory. See the
modprobe manual page (man modprobe) for
much more information on configuring and using modprobe.