To load a kernel module, run modprobe <module_name> as root. For example, to load the wacom module, run:

~]# modprobe wacom

By default, modprobe attempts to load the module from /lib/modules/<kernel_version>/kernel/drivers/. In this directory, each type of module has its own subdirectory, such as net/ and scsi/, for network and SCSI interface drivers respectively.

Some modules have dependencies, which are other kernel modules that must be loaded before the module in question can be loaded. The modprobe command always takes dependencies into account when performing operations. When you ask modprobe to load a specific kernel module, it first examines the dependencies of that module, if there are any, and loads them if they are not already loaded into the kernel. modprobe resolves dependencies recursively: it will load all dependencies of dependencies, and so on, if necessary, thus ensuring that all dependencies are always met.

You can use the -v (i.e. --verbose) option to cause modprobe to display detailed information about what it is doing, which may include loading module dependencies. Here's an example of loading the Fibre Channel over Ethernet module verbosely:

~]# modprobe -v fcoe
insmod /lib/modules/2.6.32-71.el6.x86_64/kernel/drivers/scsi/scsi_tgt.ko
insmod /lib/modules/2.6.32-71.el6.x86_64/kernel/drivers/scsi/scsi_transport_fc.ko
insmod /lib/modules/2.6.32-71.el6.x86_64/kernel/drivers/scsi/libfc/libfc.ko
insmod /lib/modules/2.6.32-71.el6.x86_64/kernel/drivers/scsi/fcoe/libfcoe.ko
insmod /lib/modules/2.6.32-71.el6.x86_64/kernel/drivers/scsi/fcoe/fcoe.ko

Example 22.2, “modprobe -v shows module dependencies as they are loaded” shows that modprobe loaded the scsi_tgt, scsi_transport_fc, libfc and libfcoe modules as dependencies before finally loading fcoe. Also note that modprobe used the more “primitive” insmod command to insert the modules into the running kernel.