Using Boot Commands during Installation


Using Boot Commands during Installation

When you boot the PC for installation, either from a boot disk or directly from the first CD-ROM, you get a text screen with the boot: prompt. Typically, you press Enter at that prompt or do nothing and the installation begins shortly. You can, however, type quite a variety of commands at the boot prompt. The commands can provide options to the Linux kernel that takes care of the installation and controls various aspects of the installation such as whether the kernel should probe for hardware or whether to use GUI screens for the installation. Some of these commands can be helpful in bypassing problems that you may encounter during installation.

To use these boot commands, you type the word linux followed by the boot command. For example, to perform text-mode installation and tell the kernel that your PC has 256MB of memory, you’d type the following at the boot prompt:

linux text mem=256M

Consult Table 2-3 for a brief summary of the boot commands.

Insider Insight 

A few of the boot commands do not require you to type linux first. You can simply type text to enter text-mode installation and expert to run the installation in expert mode.

Table 2-3: Linux Boot Commands for Red Hat Linux Installation

Command

Description

askmethod

Prompts you for other installation methods such as install over the network using NFS, FTP, or HTTP

apic

Works around a bug commonly encountered in the Intel 440GX chipset BIOS and should only be executed with the installation program kernel

apm=allow_ints

Changes how the laptop can be suspended

apm=off

Disables APM (Advanced Power Management) in case a BIOS has a buggy APM

apm=power_off

Causes Red Hat Linux to power off the system (useful for symmetric multiprocessing—SMP—systems that do not shut down by default)

apm=realmode_power_off

Causes APM to work the way it does in Windows 95 instead of how it works in Windows NT (useful if BIOS crashes when trying to shut down the machine)

dd

Prompts for a driver disk during the installation of Red Hat Linux

display=IP_address:0

Causes installer GUI to appear on the remote system identified by the IP address (make sure that you run the command xhost +hostname on the remote system where hostname is the host where you are running the installer)

driverdisk

Performs the same function as the dd command

expert

Enables you to partition removable media and prompts for a driver disk

ide=nodma

Disables DMA (direct memory access) on all IDE devices and can be useful when you are having IDE-related problems

isa

Prompts you for the configuration of older ISA devices—the older IBM-compatible PC architecture) devices

ks

Configures the Ethernet card using DHCP and then runs a kickstart installation by using a kickstart file from an NFS server identified by the bootServer parameters provided by the DHCP server

ks=kickstartfile

Runs a kickstart installation by using the kickstart file specified by kickstartfile (see the “Using kickstart Installation” section for the format of the kickstartfile specification)

lowres

Forces the installer GUI to run at a lower resolution (640x480)

mediacheck

Prompts you if you want to check the integrity of the CD image (also called ISO image). This is done by computing the MD5 checksum and comparing that with the official Red Hat provided value. It can take a few minutes to check a CD-ROM.

mem=xxxM

Overrides the amount of memory the kernel detects in the PC (some older machines could detect only 16MB of memory, and on some new machines the video card may use a portion of the main memory). Replace xxx with the number representing the megabytes of memory in your PC.

nmi_watchdog=1

Enables the built-in kernel deadlock detector that makes use of Non Maskable Interrupt (NMI)

noapic

Prevents the kernel from using the Advanced Programmable Interrupt Controller (APIC) chip (use this on motherboards known to have a bad APIC)

nofirewire

Does not load support for FireWire

noht

Disables hyperthreading (a feature available in some SMP systems)

nomce

Disables self-diagnosis checks performed on the CPU by using Machine Check Exception (MCE). On some machines these checks are performed too often and need to be disabled.

nomount

Does not automatically mount any installed Linux partitions in rescue mode

nopass

Does not pass the keyboard and mouse information to stage 2 of the installation program

nopcmcia

Ignores any PCMCIA controllers in system

noprobe

Disables automatic hardware detection and instead prompts the user for information about SCSI and network hardware installed on the PC. You can pass parameters to modules by using this approach.

noshell

Disables shell access on virtual console 2 (the one you get by pressing Ctrl-Alt-F2) during installation

nousb

Disables the loading of USB support during the installation (may be useful if the installation program hangs early in the process)

nousbstorage

Disables the loading of the usbstorage module in the installation program’s loader. It may help with device ordering on SCSI systems.

reboot=b

Changes the way the kernel tries to reboot the PC so that it can reboot even if the kernel hands during system shutdown

rescue

Starts the kernel in rescue mode where you get a shell prompt and can try to fix problems

resolution=HHHxVVV

Causes the installer GUI to run in the specified video mode (replace HHH and VVV with standard resolution numbers, such as 640x480, 800x600, 1024x768, and so on)

serial

Turns on serial console support during installation

skipddc

Skips the Display Data Channel (DDC) probe of monitors (useful if the probing causes problems)

text

Runs the installation program in text mode

updates

Prompts for a floppy disk containing updates (bug fixes)