Kernel Modules; Kernel Module Utilities - Red Hat ENTERPRISE LINUX 4 System Administration Manual

Chapter 37.

Kernel Modules

The Linux kernel has a modular design. At boot time, only a minimal resident kernel is loaded into
memory. Thereafter, whenever a user requests a feature that is not present in the resident kernel, a
kernel module, sometimes referred to as a driver, is dynamically loaded into memory.
During installation, the hardware on the system is probed. Based on this probing and the information
provided by the user, the installation program decides which modules need to be loaded at boot time.
The installation program sets up the dynamic loading mechanism to work transparently.
If new hardware is added after installation and the hardware requires a kernel module, the system
must be configured to load the proper kernel module for the new hardware. When the system is
booted with the new hardware, the Kudzu program runs, detects the new hardware if it is supported,
and configures the module for it. The module can also be specified manually by editing the module
configuration file, /etc/modprobe.conf.
Note
Video card modules used to display the X Window System interface are part of the xorg-
X11 packages, not the kernel; thus, this chapter does not apply to them.
For example, if a system included an SMC EtherPower 10 PCI network adapter, the module
configuration file contains the following line:
alias eth0 tulip
If a second network card is added to the system and is identical to the first card, add the following line
to /etc/modprobe.conf:
alias eth1 tulip
Refer to the Reference Guide for an alphabetical list of kernel modules and supported hardware for
those modules.

37.1. Kernel Module Utilities

A group of commands for managing kernel modules is available if the module-init-tools package
is installed. Use these commands to determine if a module has been loaded successfully or when
trying different modules for a piece of new hardware.
The command /sbin/lsmod displays a list of currently loaded modules. For example:
Module
nfs
lockd
parport_pc
lp
parport
autofs4
i2c_dev
i2c_core
sunrpc
Size Used by
218437 1
63977 2 nfs
24705 1
12077 0
37129 2 parport_pc,lp
23237 2
11329 0
22081 1 i2c_dev
157093 5 nfs,lockd
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