Modules

Sometime before the 2.0.x kernels, modularized drivers were first introduced

into the kernel. This was a pretty shaky interface at first, and some drivers

worked very well while others didn't work at all. By the 2.0 kernel the use

of modules was a well understood method. While there are still occasional

problems associated with modular drivers, this feature of the Linux kernel have

become one of the stable workhorses of the present day operating system.

Advantages

  Smaller kernel image

  More versatility in installation environments

  Driver modification/testing without kernel reboot

  Reduction in memory usage.

Almost every driver can be built as a module. If the kernel was built with

module support and kerneld enabled, then most modules will not need any

special entries in the /etc/modules file. kerneld will load them when they are

needed and unload them when they are not being used. Some modules need to

be loaded and initialized by the kernel before kerneld is started by init. There

is a line in the provided /etc/modules file, after the general comments, that

has been commented out. This is the  auto  line. Removing the comment

(# character) from the  auto  line, will tell the kernel to load those modules

automatically, without the aid of kerneld.

Some device drivers, like the low level drivers for specific SCSI cards, must be

installed explicitly. When a CD is mounted, the system (and kerneld) know

that the modules that support the SCSI device must be loaded. The kernel

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