Device Drivers in Linux
From Free Knowledge Base- The DUCK Project: information for everyone
- Linux device driver kernel files are in /dev
- Drivers are either compiled into the kernel, or loaded as kernel modules
- Linux device driver kernel modules can be configured, loaded, unloaded without rebooting the system
- Not all device drivers are kernel devices, such as video drivers for xwindows
- The programs insmod, rmmod, ksyms, lsmod, genksyms, modprobe, and depmod are part of "module utilities" and when installed, the commands are in /sbin
Loading a Device Driver Kernel Module:
Use modprobe to load a kernel module into the running kernel. You can specify parameters with modprobe too.
modeprobe <module name>
Other commands, such as to show the loaded modules or inserting a module into the running kernel
lsmod insmod
Modules usually have an extension of ".o"
Modules can be loaded when the system boots. They are specified in the text configuration file: /etc/modules It contains a list of modules to be loaded. Options for the modules are in the file: /etc/conf.modules Rather than directly editing the conf.modules with vi, use the script provided for that purpose
update-modules
Unloading a Device Driver Kernel Module:
If the module is not used by the system, it may be unloaded by either of the following methods:
modprobe -r <module_name> rmmod <module_name>
lsmod - list loaded modules insmod - install loadable kernel module modprobe - high level handling of loadable modules depmod - handle dependency descriptions for loadable kernel modules rmmod - unload loadable modules ksyms - display exported kernel symbols udevadm - device manager for the Linux kernel replacing devfsd and hotplug. manages device nodes in the /dev directory
