Introduction

This page discusses the options available to alter the boot of an installed Ubuntu or an Ubuntu CD. It briefly details the main start options and then focuses on various options to alter the boot process. Changing the boot command may be necessary to fix problems with system freezes or video displays when trying to install Ubuntu. It may also be helpful when an existing installation will not boot or otherwise needs adjustment.

Some remedies, such as using the F1-F6 keys, are specific to the CD boot process. Other procedures, such as editing the boot menu lines, can be used on either the LiveCD or on an installed system.

For help with directly editing the Grub configuration files or other installation issues please refer to the links at the bottom of this page.

Ubuntu CD Welcome Page Options

When the Ubuntu CD is started and not interrupted the CD will boot to a welcome screen which gives the user the option to install or try Ubuntu. This screen will remain visible until a selection is made.

Ubuntu CD Advanced Welcome Page Options

As the CD boots, the user can gain access to the advanced page and its options by pressing any key when the small logo appears at the bottom of your screen:

Here is the advanced welcome page:

Here is a brief explanation of each main option:

Changing the CD's Default Boot Options

To supplement the main boot options, the F1-F6 keys provide additional information and boot options for special circumstances. These options are accessed by pressing any key before the Welcome screen appears. Pressing the ESC key or selecting a language will display the main screen.

Although they are not normally needed, these options provide additional assistance in getting the CD to boot for a variety of issues. Any changes made will affect the current boot only and must be made each time the CD is booted.

Changing the CD Boot Option Configuration Line

In addition to displaying a popup menu, the F6 key also activates in-line editing of the boot command. Pressing F6 brings up the popup menu. Pressing ESC, whether selections were made or not, removes the popup window but opens the boot command for editing. The phrase "Boot Options" is fixed on the left side of the screen. The command scrolls off to the left to leave the right end available for appending. The user may add additional inputs before or after the "-- ". Allow one space between each additional input.

The "-- " entry defines the boundary between options which are specific to the installer and ones that are copied to the target system. Often you would like to copy the boot option to the target system, so add the option at the very end of the line, after the "-- ".

This link describes a new way to use a boot option. Sometimes it must be entered twice, before and after the delimiter "-- ". We find it in Ubuntu Server 14.04.2 and when testing future versions, and we expect it to come into the Ubuntu mini.iso file with the version 15.04.

Changing boot options Temporarily for an Existing Installation

See the Grub2 page.

Changing boot options Permanently for an Existing Installation

This can be done by :

http://pix.toile-libre.org/upload/img/1312988983.png

Common Kernel Options

This list is not comprehensive but it contains some common boot options which may be added to the end of the boot command.

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

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. Option two modifies the list of supported OS interface strings (changes the OS compatibility reported to the BIOS). Necessary on some broken BIOSes to make temperature/fan control work.

See Also


CategoryInstallation

BootOptions (last edited 2020-05-20 22:26:00 by mclemenceau)