Your Hardware and Kudzu

When you add or replace hardware, for example, you will need to configure the operating system to recognize and boot with the new components working properly. If you have enabled the kudzu service, Fedora will automatically detect new hardware upon rebooting; Kudzu then enables you to remove configuration information about missing hardware and configure the new device. If you do not use Kudzu, however, you might need to perform configuration manually without the support of automated hardware detection and configuration.

NOTE

The kudzu service maintains a database of your system's hardware information under the /etc/sysconfig directory in a file named hwconf. This service can be started, stopped, or restarted (like other operating system services) from the command line by using a script under the /etc/rc.d/init.d directory (named kudzu). You can add options or enable various features of Kudzu, such as timeouts, by editing the KUDZU_ARGS= entry in the kudzu script (see the kudzu man page for the options). You can also use the command-line based service command or the graphical system-config-services client to control kudzu. See Chapter 14, "Automating Tasks," for more information on using these commands.

You can perform many post-installation tasks without rebooting or downtime. With proper planning, you also can create a server or workstation configuration that allows "hot-swapping" of system storage and other components, eliminating the need for downtime. In this chapter, you learn how to configure various USB and Firewire (IEEE-1394) devices in addition to keyboards, modems, and notebook PCMCIA services.

Information about your system's installed hardware is contained in a number of files under the Fedora directory system. Aside from one or two symbolic links, or shortcut-type files created under the /dev directory for the convenience of system utilities, nearly all these hardware settings are in text files under the /etc directory. The contents of these files are used by various software services to manage your system's hardware, save changes to your hardware, ensure that settings are saved between reboots, and to properly configure your system upon booting. A number of these files are used by the /etc/rc.d/rc.sysinit script when Linux starts. For example, some of these files include

/etc/sysconfig/hwconf Lists the currently configured system hardware (used by kudzu)

/etc/sysconfig/apmd Lists system power-management settings (used by the apmd deamon)

/etc/sysconfig/clock Contains time zone, clock, and hardware clock settings (used by the hwclock command)

/etc/sysconfig/harddisks System hard drive tuning parameters (using options available with the hdparm command)

/etc/sysconfig/irda Provides configuration data concerning Infrared Data Association (IrDA) hardware

/etc/sysconfig/keyboard Lists current keyboard mapping (and provides language settings)

/etc/sysconfig/mouse Details the current system pointing device (such as whether or not a PS2 or USB mouse is used)

/etc/modprobe.conf Defines device names, kernel hardware support modules to load, and any optional parameters (see Chapter 38, "Kernel and Module Management," for more information about Linux kernel modules)

/etc/pcmcia A directory containing a Personal Computer Memory Card International Association (PCMCIA) hardware database and device settings (see the section "Managing PCMCIA" later in this chapter)

You will find additional information about the files in /etc/sysconfig in the file named sysconfig.txt under the /usr/share/doc/initscripts directory.

CAUTION

Do not edit kudzu's text-file database of installed hardware; these files are updated dynamically by Kudzu. If you have trouble with a device, however, you can check the information in these files when troubleshooting to see if the device is properly recognized and its definition matches the actual hardware.