Red Hat Enterprise Linux 5 Administration Unleashed

Listing and Configuring Kernel Modules 163Querying Vendor-Specific DataThe dmidecode RPM package also includes the ownership and vpddecode utilities. Theownership utility is a specialized command for Compaq computers. If biosdecode displaysinformation about 32OS data, the ownership command can retrieve the Compaq ownershiptag. The vpddecode utility is also for a specific set of computers. It only works on IBMcomputers to display the vital product data from the system. If VPD data is found in thebiosdecode query, use the vpddecode command to query for more information. Theoutput includes the BIOS build ID, product name, box serial number, motherboard serialnumber, and machine type/model. Some systems output more information such as BIOSrelease date.Listing and Configuring Kernel ModulesFor a piece of hardware to work properly in Red Hat Enterprise Linux, the associatedkernel module must be loaded. The kernel module allows the kernel and end-userprograms to interact with the hardware.To view a list of all currently loaded kernel modules, use the lsmod command. It can berun as a normal user or as root, but if run as a non-root user, you might need to specifythe full path to the command, /sbin/lsmod, because /sbin/ is not in the default path of anon-root user.TIPTo manually load a module, use the modprobe command. The specifiedmodule will be loaded along with any module dependencies.6The module to use for some hardware such as network cards, sound cards, and USBcontrollers are saved in /etc/modprobe.conf so they don’t have to be configured eachtime the system boots. Other modules are loaded as needed from the utilities that requirethem. For example, when the mount command is used to mount a Samba share, the smbfsmodule is loaded.Kernel module options can also be added to /etc/modprobe.conf to tweak the modulesettings. To determine what parameters are available, use the modinfo command. The beginning of the modinfo outputs displays the full path to the kernelmodule, software license for the module, description, and author as shown in Listing 6.12for the 3c59x module.LISTING 6.12filename:license:description:author:Beginning of Module Information for 3c59x Module/lib/modules/2.6.18-1.2839.el5xen/kernel/drivers/net/3c59x.koGPL3Com 3c59x/3c9xx ethernet driverDonald Becker