Chapter 20. Additional Boot Options

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.

You can also store kernel boot options for the z/IPL boot loader in the zipl.conf file, either by editing the file manually or using the zipl tool.

Kernel parameters in `zipl.conf` that contain quotation marks

Where kernel parameters use nested quotation marks, the required order in Red Hat Enterprise Linux is double quote marks for the outer set and single quote marks for the inner set. For example, parameters="vmhalt='LOGOFF'" is correct, while parameters='vmhalt="LOGOFF"' is not correct and may lead to unexpected behavior.

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.
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.
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.
mpath: enables multipath support.
Important — mandatory for installation on multipath devices
If you install Red Hat Enterprise Linux 5.8 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.
noeject: do not eject optical discs after installation. This option is useful in remote installations where it is difficult to close the tray afterwards.
noprobe: this command disables hardware detection and instead prompts the user for hardware information.
rescue: this command runs rescue mode. Refer to Chapter 27, Basic System Recovery for more information about rescue mode.
text: this command disables the graphical installation program and forces the installation program to run in text mode.
vnc: this command allows you to install from a VNC server.
vncpassword=: this command sets the password used to connect to the VNC server.
noipv6: this command disables the default selection of ipv6 options during the installer stage 1 processing. Ipv6 settings may still be made manually if this option is specified, but the default behavior will be that Ipv6 settings are not enabled.
cmdline: The 3270 console (most often used during installation on IBM System z) does not recognize terminal formatting entries common to most unix-style terminals. Specifying this option changes the behavior of anaconda during kickstart installations so that console output on the 3270 is much better. This option should not be used for regular, interactive installations.
RUNKS=1: This option is used to specify (usually in conjunction with the cmdline option) kickstart installation for IBM System z.