Thursday, January 13, 2011

BootOptions - Community Ubuntu Documentation

Common Boot Options

This list is not comprehensive but it contains some common boot options. When presented with the text on the screen "boot:" then the boot options below can be given. They must have the kernel name before the option.

Example

Adding the vga=771 option:

boot: /boot/vmlinuz-2.6.15-26-k7 root=/dev/hda1 ro quiet splash

boot: /boot/vmlinuz-2.6.15-26-k7 root=/dev/hda1 ro quiet splash vga=771

Options can be used together such as in this example:

/boot/vmlinuz-2.6.15-26-k7 root=/dev/hda1 ro quiet splash noapic nolapic

Kernel Options

Note: These options are used by the kernel, and will apply to any installation at any time. The file "Documentation/kernel-parameters.txt" in the relevant linux-source package provides more information.

Option

Impact

vga=xxx

Set your framebuffer resolution to VESA mode xxx. Check here for a list of possible modes.

acpi=off OR noacpi

This parameter disables the whole ACPI system. This may prove very useful, for example, if your computer does not support ACPI or if you think the ACPI implementation might cause some problems (for instance random reboots or system lockups).

acpi=force

Activates the ACPI system even if your computer BIOS date is older than 2000. This parameter overrides acpi=off and can also be used with current hardware if the ACPI support is not activated despite apm=off.

pci=noacpi OR acpi=noirq

These parameters disable the PCI IRQ routing

pci=acpi

This parameter activates the PCI IRQ routing

acpi_irq_balance

ACPI is allowed to use PIC interrupts to minimize the common use of IRQs.

acpi_irq_nobalance

ACPI is not allowed to use PIC interrupts.

acpi=oldboot

Deactivates the ACPI system almost completely; only the components required for the boot process will be used.

acpi=ht

Impact Deactivates the ACPI system almost completely; only the components required for hyper threading will be used.

noapic

Disable the "Advanced Programmable Interrupt Controller (APIC)".

nolapic

Disable the "local APIC".

apm=off OR noapm

Disable the Advanced Power Management.

irqpoll

Changes the way the kernel handles interrupt calls (set it to polling). Can be useful in case of hardware interrupt issues.

acpi.power_nocheck=1 OR acpi_osi=linux

Disable the check of power state or changes the OS compatibility reported to the BIOS. Necessary on some broken BIOSes to make temperature/fan control work.

Text Mode

Option

Impact

nosplash

Disables splash screen.

text OR -s OR s OR S OR Single

Disables gdm.

console=ttyXX

Multiple console= are allowed. Last one listed gets start-up messages (stdin/stdout/stderr of /sbin/init). Common: console=ttyS0,115200n8

Initrd break points

These options will cause the initrd to pause execution and spawn a shell. Only one option at a time may be specified (the last wins). See also: /usr/share/initramfs-tools/init and /usr/share/initramfs-tools/scripts/*.

Option

Impact

break=top

Break before any scripts are run (including usplash)

break=modules

Break before any modules are loaded

break OR break=premount

Break before the premount scripts are run (ie: udev)

break=mount

Break before the root partition is mounted

break=bottom

Break before the 'bottom' scripts are run

break=init

Break just before control is handed over to /sbin/init.

(Please feel free to add some options.)

Installer options (user-land)

These options are usually used when installing a system, and are picked up by the installer program or start-up scripts, and not by the kernel.

Option

Impact

debian-installer/framebuffer=false

Disable framebuffer.

hw-detect/start_pcmcia=false

Don't start PCMCIA.

netcfg/disable_dhcp=true

Force static network config.

bootkbd=uk

Set keyboard map. Use a two letter ISO country code to get the right letters on the right keys. This option can help with password problems.

cdrom-detect/try-usb=true

Enable search for usb device (cdrom, memorystick, harddrive) with casper file and boot it.

xforcevesa

Force X to start using VESA driver. Useful for some notebooks with uncommon video interfaces.

(This list is far from complete, please feel free to add some options.)

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