A tutorial on using the Lsmod command (listing Kernel units)

lsmod is a command-line utility that displays information about loaded Linux kernel modules.

Kernel module

The kernel is the primary component of an operating system. The kernel manages everything in an operating system, including all system resources, and is the bridge between your computer hardware and software.

Linux kernel has a modular design. Kernel modules, or often referred to as drivers, are pieces of code that extend the functionality of the kernel. This module can be compiled as a module that can be loaded into the operating system or part of the kernel itself. These downloadable modules can be unloaded into the running kernel on demand, without rebooting the system.

Generally, units are loaded on demand by udev (device Manager). You can also load modules manually into the kernel using commands modprobe, Or automatically when booting with /etc/modules Or in a file /etc/modules-load.d/*.conf.

Kernel units are stored in directories /lib/modules/<versi_kernel>. To find a running kernel version, use the command uname -r.

Lsmod command

lsmod is a simple utility that does not accept any options or arguments. The thing is reading what’s going on /proc/modules It displays the contents of the file in a properly formatted list.

Running around lsmod On the command line to see which kernel modules are currently loaded:

lsmod

The command displays information for each kernel unit loaded on a new line:

Module                  Size  Used by
cmac                   16384  0
rfcomm                 81920  4
...
ahci                   40960  1
intel_lpss_pci         20480  0
i2c_i801               32768  0
libahci                32768  1 ahci
intel_lpss             16384  1 intel_lpss_pci
...

Each row contains three columns:

  • Module – The first column shows the unit name.
  • Size – The second column shows the unit size in bytes.
  • Used by – The third column shows a number indicating the number of instances of the unit currently in use. A zero value means that the unit is not used. A comma-separated list after the number shows what the unit is using.

To see if a specific unit is loaded, filter the output with grep. For example to see if the module kvm After downloading, you can run the following command:

lsmod | grep kvm
kvm_intel             278528  0
kvm                   651264  1 kvm_intel
irqbypass              16384  1 kvm

To get detailed information about the module, use the command modinfo.

Conclusion

The lsmod command displays a list of currently loaded kernel modules.

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