Chapter 8. Additional Boot Options for Intel® and AMD Systems

This section discusses additional boot and kernel boot options available for the Red Hat Enterprise Linux installation program.
To use any of the boot options presented here, type the command you wish to invoke at the installation boot: prompt.

Boot Time Command Arguments

askmethod
this command asks you to select the installation method you would like to use when booting from the Red Hat Enterprise Linux CD-ROM.
apic
this x86 boot command works around a bug commonly encountered in the Intel 440GX chipset BIOS and should only be executed with the installation program kernel.
dd
this argument causes the installation program to prompt you to use a driver diskette.
dd=url
this argument causes the installation program to prompt you to use a driver image from a specified HTTP, FTP, or NFS network address.
display=ip:0
this command allows remote display forwarding. In this command, ip should be replaced with the IP address of the system on which you want the display to appear.
On the system you want the display to appear on, you must execute the command xhost +remotehostname, where remotehostname is the name of the host from which you are running the original display. Using the command xhost +remotehostname limits access to the remote display terminal and does not allow access from anyone or any system not specifically authorized for remote access.
driverdisk
this command performs the same function as the dd command and also prompts you to use a driver diskette during the installation of Red Hat Enterprise Linux.
linux upgradeany
this command relaxes some of the checks on your /etc/redhat-release file. If your /etc/redhat-release file has been changed from the default, your Red Hat Enterprise Linux installation may not be found when attempting an upgrade to Red Hat Enterprise Linux 5. Use this option only if your existing Red Hat Enterprise Linux installation was not detected.
mediacheck
this command gives you the option of testing the integrity of the install source (if an ISO-based method). this command works with the CD, DVD, hard drive ISO, and NFS ISO installation methods. Verifying that the ISO images are intact before you attempt an installation helps to avoid problems that are often encountered during an installation.
mem=xxxm
this command allows you to override the amount of memory the kernel detects for the machine. This may be needed for some older systems where only 16 mb is detected and for some new machines where the video card shares the video memory with the main memory. When executing this command, xxx should be replaced with the amount of memory in megabytes.
mpath
enables multipath support.

Important

If you install Red Hat Enterprise Linux 5.11 on a network storage device accessible through multiple paths, you must boot the installation process with this option. If you do not specify this option at boot time, installation will fail, or the system will fail to boot after installation completes.
nmi_watchdog=1
this command enables the built-in kernel deadlock detector. This command can be used to debug hard kernel lockups. by executing periodic NMI (Non Maskable Interrupt) interrupts, the kernel can monitor whether any CPU has locked up and print out debugging messages as needed.
noapic
this x86 boot command tells the kernel not to use the APIC chip. It may be helpful for some motherboards with a bad APIC (such as the Abit BP6) or with a buggy bios. systems based on the nvidia nforce3 chipset (such as the Asus SK8N) have been known to hang during IDE detection at boot time, or display other interrupt-delivery issues.
noeject
do not eject optical discs after installation. This option is useful in remote installations where it is difficult to close the tray afterwards.
nomce
this x86 boot command disables self-diagnosis checks performed on the CPU. the kernel enables self-diagnosis on the CPU by default (called machine check exception). Early Compaq Pentium systems may need this option as they do not support processor error checking correctly. A few other laptops, notably those using the Radeon IGP chipset, may also need this option.
nonet
this command disables network hardware probing.
nopass
this command disables the passing of keyboard and mouse information to stage 2 of the installation program. It can be used to test keyboard and mouse configuration screens during stage 2 of the installation program when performing a network installation.
nopcmcia
this command ignores any PCMCIA controllers in system.
noprobe
this command disables hardware detection and instead prompts the user for hardware information.
noshell
this command disables shell access on virtual console 2 during an installation.
nostorage
this command disables probing for SCSI and RAID storage hardware.
nousb
this command disables the loading of USB support during the installation. If the installation program tends to hang early in the process, this command may be helpful.
nousbstorage
this command disables the loading of the usbstorage module in the installation program's loader. It may help with device ordering on SCSI systems.
numa=off
Red Hat Enterprise Linux supports NUMA (non-uniform memory access) on the AMD64 architecture. while all cpus can access all memory even without numa support, the numa support present in the updated kernel causes memory allocations to favor the cpu on which they originate as much as possible, thereby minimizing inter-CPU memory traffic. This can provide significant performance improvements in certain applications. to revert to the original non-NUMA behavior, specify this boot option.
reboot=b
this x86, AMD64, and Intel® EM64T boot command changes the way the kernel tries to reboot the machine. If a kernel hang is experienced while the system is shutting down, this command may cause the system to reboot successfully.
rescue
this command runs rescue mode. Refer to Chapter 27, Basic System Recovery for more information about rescue mode.
resolution=
tells the installation program which video mode to run. it accepts any standard resolution, such as 640x480, 800x600, 1024x768, and so on.
serial
this command turns on serial console support.
text
this command disables the graphical installation program and forces the installation program to run in text mode.
updates
this command prompts you to insert a floppy diskette containing updates (bug fixes) for the anaconda installation program. It is not needed if you are performing a network installation and have already placed the updates image contents in rhupdates/ on the server.
updates=
this command allows you to specify a URL to retrieve updates (bug fixes) for the anaconda installation program.
vnc
this command allows you to install from a VNC server.
vncpassword=
this command sets the password used to connect to the VNC server.

Important

Other kernel boot options have no particular meaning for anaconda and do not affect the installation process. However, if you use these options to boot the installation system, anaconda will preserve them in the bootloader configuration.