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NOTE: CentOS Enterprise Linux is built from the Red Hat Enterprise Linux source code. Other than logo and name changes CentOS Enterprise Linux is compatible with the equivalent Red Hat version. This document applies equally to both Red Hat and CentOS Enterprise Linux.

Appendix A. General Parameters and Modules

This appendix is provided to illustrate some of the possible parameters available for common hardware device drivers[1], which under Red Hat Enterprise Linux are called kernel modules. In most cases, the default parameters do work. However, there may be times when extra module parameters are necessary for a device to function properly or to override the module's default parameters for the device.

During installation, Red Hat Enterprise Linux uses a limited subset of device drivers to create a stable installation environment. Although the installation program supports installation on many different types of hardware, some drivers (including those for SCSI adapters and network adapters) are not included in the installation kernel. Rather, they must be loaded as modules by the user at boot time. For information about extra kernel modules during the installation process, refer to the section concerning alternative boot methods in the chapter titled Steps to Get You Started in the Red Hat Enterprise Linux Installation Guide.

Once installation is completed, support exists for a large number of devices through kernel modules.

Important Important

Red Hat provides a large number of unsupported device drivers in a group of packages called kernel-unsupported-<kernel-version>, kernel-smp-unsupported-<kernel-version>, and kernel-hugemem-unsupported-<kernel-version>. Replace <kernel-version> with the version of the kernel installed on the system. These packages are not installed by the Red Hat Enterprise Linux installation program, and the modules provided are not supported by Red Hat, Inc.

A.1. Specifying Module Parameters

In some situations, it may be necessary to supply parameters to a module as it is loaded for it to function properly.

For instance, to enable full duplex at 100Mbps connection speed for an Intel Ether Express/100 card, load the e100 driver with the e100_speed_duplex=4 option.

Caution Caution

When a parameter has commas, be sure not to put a space after a comma.

Tip Tip

The modinfo command is also useful for listing various information about a kernel module, such as version, dependencies, paramater options, and aliases.



A driver is software which enables Linux to use a particular hardware device. Without a driver, the kernel cannot communicate with attached devices.

  Published under the terms of the GNU General Public License Design by Interspire