Howto: Add or Remove a Linux Kernel Modules

How do I add or remove hardware device driver (module) from running Linux kernel? Linux systems comes with the modprobe command, to add and remove modules from the Linux Kernel and prevent your system from load unnecessary modules.

Please note that:

=> Under MS-Windows you use term device driver for modules.

=> Under Linux you use term modules for device drivers.

=> The Linux kernel has a modular design.

=> At boot time, only a minimal resident kernel is loaded into memory.

=> If you add new hardware you need to add driver i.e. modules.

=> The modprobe command intelligently adds or removes a module from the Linux kernel

=> Usually, all Linux kernel modules (drivers) are stored in the module directory located that
/lib/modules/$(uname -r) directory. To see current modules, type:

$ ls /lib/modules/$(uname -r)


build                modules.ccwmap       modules.order
initrd               modules.dep          modules.pcimap
kernel               modules.dep.bin      modules.seriomap
misc                 modules.devname      modules.softdep
modules.alias        modules.ieee1394map  modules.symbols
modules.alias.bin    modules.inputmap     modules.symbols.bin
modules.builtin      modules.isapnpmap    modules.usbmap
modules.builtin.bin  modules.ofmap        updates

Use the following command to list all drivers for various devices:

$ ls /lib/modules/$(uname -r)/kernel/drivers/

Sample outputs:

Fig.01: Device drivers on my Linux based system

Task: Add a Module (driver) Called foo

You should type the following command as root user:

# modprobe foo

In this example, I am loading a module called i8k, enter:

# modprobe -v i8k

Sample outputs:

insmod /lib/modules/3.5.0-30-generic/kernel/drivers/char/i8k.ko

Find out info about loaded module

You need to use the modinfo command to see information about a Linux Kernel module. The syntax is:

# modinfo -v {module-name-here}
# modinfo i8k

Sample outputs:

Fig.02: Displaying information about a Linux Kernel module called i8k

Task: List all loaded modules

Use the lsmod command to show the status of modules in the Linux Kernel:

# lsmod

Sample outputs:

Module                  Size  Used by
smbfs                  75465  0
md5                     5953  1
ipv6                  284193  10
ipt_TOS                 4033  2
iptable_mangle          4545  1
ip_conntrack_ftp       74801  0
ip_conntrack_irc       74033  0
ipt_REJECT              8897  43
ipt_LOG                 8513  2
ipt_limit               4033  6
iptable_filter          4673  1
ipt_multiport           3521  4
ipt_state               3393  16
ip_conntrack           54297  3 ip_conntrack_ftp,ip_conntrack_irc,ipt_state
ip_tables              21825  8 ipt_TOS,iptable_mangle,ipt_REJECT,ipt_LOG,ipt_limit,iptable_filter,ipt_multiport,ipt_state
i2c_dev                13889  0
i2c_core               28865  1 i2c_dev
dm_mirror              32721  0
dm_mod                 68609  1 dm_mirror
button                  9313  0
battery                11465  0
ac                      6985  0
ohci_hcd               24529  0
ehci_hcd               33989  0
tg3                   109381  0
floppy                 66065  0
ext3                  137937  2
jbd                    69105  1 ext3
sata_svw               10053  3
libata                 78345  1 sata_svw
sd_mod                 19393  4
scsi_mod              141457  2 libata,sd_mod

Task: Remove a module called foo

Pass the -r option to modprobe command to remove a module, type:

# modprobe -r foo

You can also use the rmmod command, which is simple program to remove a module from the Linux Kernel:

# rmmod foo
  • man pages – modinfo, lsmod, insmod, and modprobe


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