How to Load and Unload Kernel Modules in Linux
A kernel module is a program which can loaded into or unloaded from the kernel upon demand, without necessarily recompiling it (the kernel) or rebooting the system, and is intended to enhance the functionality of the kernel.
In general software terms, modules are more or less like plugins to a software such as WordPress. Plugins provide means to extend software functionality, without them, developers would have to build a single massive software with all functionalities integrated in a package. If new functionalities are needed, they would have to be added in new versions of a software.
Likewise without modules, the kernel would have to be built with all functionalities integrated directly into the kernel image. This would mean having bigger kernels, and system administrators would need to recompile the kernel every time a new functionality is needed.
A simple example of a module is a device driver – which enables the kernel to access a hardware component/device connected to the system.
List All Loaded Kernel Modules in Linux
In Linux, all modules end with the .ko extension, and they are normally loaded automatically as the hardware is detected at system boot. However a system administrator can manage the modules using certain commands.
To list all currently loaded modules in Linux, we can use the lsmod (list modules) command which reads the contents of /proc/modules like this.
Module Size Used by rfcomm 69632 2 pci_stub 16384 1 vboxpci 24576 0 vboxnetadp 28672 0 vboxnetflt 28672 0 vboxdrv 454656 3 vboxnetadp,vboxnetflt,vboxpci bnep 20480 2 rtsx_usb_ms 20480 0 memstick 20480 1 rtsx_usb_ms btusb 45056 0 uvcvideo 90112 0 btrtl 16384 1 btusb btbcm 16384 1 btusb videobuf2_vmalloc 16384 1 uvcvideo btintel 16384 1 btusb videobuf2_memops 16384 1 videobuf2_vmalloc bluetooth 520192 29 bnep,btbcm,btrtl,btusb,rfcomm,btintel videobuf2_v4l2 28672 1 uvcvideo videobuf2_core 36864 2 uvcvideo,videobuf2_v4l2 v4l2_common 16384 1 videobuf2_v4l2 videodev 176128 4 uvcvideo,v4l2_common,videobuf2_core,videobuf2_v4l2 intel_rapl 20480 0 x86_pkg_temp_thermal 16384 0 media 24576 2 uvcvideo,videodev .
How to Load and Unload (Remove) Kernel Modules in Linux
To load a kernel module, we can use the insmod (insert module) command. Here, we have to specify the full path of the module. The command below will insert the speedstep-lib.ko module.
# insmod /lib/modules/4.4.0-21-generic/kernel/drivers/cpufreq/speedstep-lib.ko
To unload a kernel module, we use the rmmod (remove module) command. The following example will unload or remove the speedstep-lib.ko module.
# rmmod /lib/modules/4.4.0-21-generic/kernel/drivers/cpufreq/speedstep-lib.ko
How to Manage Kernel Modules Using modprobe Command
modprobe is an intelligent command for listing, inserting as well as removing modules from the kernel. It searches in the module directory /lib/modules/$(uname -r) for all the modules and related files, but excludes alternative configuration files in the /etc/modprobe.d directory.
Here, you don’t need the absolute path of a module; this is the advantage of using modprobe over the previous commands.
To insert a module, simply provide its name as follows.
To remove a module, use the -r flag like this.
Note: Under modprobe, automatic underscore conversion is performed, so there is no difference between _ and – while entering module names.
For more usage info and options, read through the modprobe man page.
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That’s all for now! Do you have any useful ideas, that you wanted us to add to this guide or queries, use the feedback form below to drop them to us.
How to list all loadable kernel modules?
I’m looking for a few kernel modules to load i2c-dev and i2c-bcm2708 . But the modprobe command returns:
sudo modprobe i2c-dev modprobe: module i2c-dev not found in modules.dep The kernel didnt compile this i2c-dev. You didnt find this module.The kernel modules located /lib/modules/’kernel-version’/drivers. When you are looking for linux drivers.
You can check on /boot/config-‘kernel-version’ and read this config file.You should know which linux modules are loaded or modulars or during compiling kernel didnt enable i2c-dev module.
5 Answers 5
- By default modprobe loads modules from kernel subdirectories located in the /lib/modules/$(uname -r) directory. Usually all files have extension .ko , so you can list them with
find /lib/modules/$(uname -r) -type f -name '*.ko' find /lib/modules/$(uname -r) -type f -name '*.ko*' Redhat 7 modules files are compressed in .xz (not sure if it is because of kernel version or OS version.. if someone can clarify it to me?) so I think you might not find them with jimmij’s find command. Use instead find /lib/modules/$(uname -r) -type f -name *.ko*
@posinux: beware : the shell may expand your *.ko* if you happen to have in your current dir some file matching it. better to escape it between single quotes: find /lib/modules/$(uname -r) -type f -name ‘*.ko*’
Type modprobe and press tab, the autocomplete list should contain all the loadable modules
Also its double tab, and you may get prompted that there is a specific large number of entries to list, then press y to list them. Also this answer does not provide the second part to OP’s question which directory are they located?
takes very long even on newer systems and doesn’t give a really good way to look at ll the entries. just paging into one direction of 30k possibilities is probably not very much enlightening
There is lsmod command of kmod package in Arch Linux what lists and shows the status of Linux kernel modules that contains other useful commands such as modinfo , rmmod modprobe too.
To list all binaries provided by the package you can type:
pacman -Ql kmod | grep /bin/ --color=always , and you can also check for the owner package of a binary with pacman -Qo lsmod .
Q switch is to query locally installed packages (unlike S to synchronize, ie. to check remotely).
Where it’s important to highlight that lsmod only shows already loaded modules. The Author of this thread had the problem to load a module that wasn’t in the map of the loadable kernel modules. Besides, this solution only applies to archlinux. Which might be not the distribution of the Author and might not solve the problem for others.
@Akendo lsmod is also available on Ubuntu, at least. However, I agree this does not solve OP’s problem.
There is absolutely no point in talking about Arch specifically, and lsmod is a universally available command. Furthermore, the whole point of the question is to list loadable/available modules, whereas lsmod only prints listed modules. This answer should be moderated.
I prefer to use depmod . With the command: depmod -av|grep MOD_NAME , your system will generate the modules.dep/map files and grep through it. The -v parameter is important for verbosity and -a to ensure that all possible modules from /lib/modules/ are used for the modules.dep file.
This way it’s possible to ensure, that a requested kernel module is mapped to the kernel as loadable. When the desire kernel module is not listed in the output, you know that the kernel won’t find it.
According to man depmod option -a is not needed — it is enabled by default, if no file names are given in command line.
You can check how autocompletion does it:
$ complete -p modprobe complete -F _modprobe modprobe declare -f _modprobe _modprobe () < . In that function there's an internal _installed_modules
$ declare -f _installed_modules _installed_modules () < COMPREPLY=($(compgen -W "$(PATH="$PATH:/sbin" lsmod | awk '')" -- "$1")) > So lsmod | awk '' should show you the list of modules