- 1 Introduction
- 2 Main Start Page Options
- 3 Changing the CD's Default Boot Options
- 4 Change Boot Options Temporarily For An Existing Installation
- 5 Change Boot Options Permanently On An Existing Installation
- 6 Common Boot Options
- 7 See Also
This page discusses the Ubuntu | Live Desktop CD start page and the options available to alter the way the CD boots. 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 menu.lst file or other installation issues please refer to the links at the bottom of this page.
Main Start Page Options
When the Ubuntu CD is started the user gains access to its main menu by pressing ESC or selecting a language from the opened menu. If the ESC key is not pressed or no language is chosen during the 30 second timeout the CD continues to boot to the Ubuntu Desktop using the disk's default language. After selecting a language or pressing ESC the user will be presented with a screen similar to this: Here is a brief explanation of each main option:
- Try Ubuntu without any change to your computer. As indicated, selecting this option will allow Ubuntu to load and take the user to the Ubuntu desktop. Ubuntu will attempt to identify and use system hardware and allow the user to connect to the Internet. Default software such as OpenOffice and Firefox are available and the user can install additional software via Internet download. An "Install" icon is available on the Desktop should the user wish to begin the standard installation without rebooting. At the end of a | LiveCd session, unless a installation is completed, none of the changes you have made will be retained.
- Install Ubuntu. Begin the standard Ubuntu installation on the user's drive.
- Check disk for defects. This option verifies the integrity of the files contained on the CD/DVD. Press any key when the check is complete to restart the CD/DVD.
- Test memory. Selecting this option initiates Memtest86+, which runs checks on the system's memory. Allow the tests to run for at least one full pass if you suspect memory issues. This test may take a long time to run depending on the type and amount of memory. "Pass Complete" will display in the bottom center of the display once at least one pass is complete. The test will run continuously until the user presses the ESC key; this terminates the test even if it is not complete.
- Boot from first hard disk. Bypass the CD and boot from the first disk on the user's computer.
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. Although they are not normally needed, they 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.
- F1. Help index presenting information regarding prerequisites for running Ubuntu, boot methods and special boot parameters.
- F2. Language selection.
- F3. Keymap selections by country.
- F4. Graphics Modes. If video is unacceptable during the operation of the CD, selecting the "Safe graphics mode" may provide better results during LiveCD operation or until video issues can be resolved after installation.
- F5. Accessibility Options. Various options to assist users with visual impairment, as well as an onscreen keyboard option and keyboard modifiers. To employ these features use the arrow keys to highlight the option and press ENTER. Repeat this for each additional option desired. To remove all options, highlight "None" and press ENTER. Selected options will be loaded during boot. Accessibility options may also be added after installation. Look for Assistive Technologies and at-spi in Synaptic.
- F6. Other Options. ACPI (Advanced Configuration and Power Interface) and EDD (Enhanced Disk Drive) options which may help if your computer does not support or has problems with these systems. Highlight the selection and press the ENTER key or SPACE key to select it. An "X" will appear, indicating selection. Multiple items can be selected from this popup menu. Hit ESC to leave the popup menu. The selections are retained at the time the user presses the ESC key.
Changing the 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 after the "-- ". Allow one space between each additional input. A list of Common|Boot Options which can be added to the command line is presented later on this page. Above is an example of adding the vga=771 option to the end of the Boot Options line. Note the space following "--". To make an addition to the boot command:
- Press the F6 key.
- If desired, select one or more options with the arrow keys, then press ENTER or the SPACE key to select them.
- Any popup menu option enabled when ESC is pressed is retained.
- Press ESC to remove the popup screen. The boot command line is now available for editing and will remain so as long as no popup menu is visible.
- Leave a space following the "--" and add the desired option. If entering multiple options leave a space between each entry.
- The command will be executed when ENTER is pressed and the boot sequence will begin.
- The F1-F6 keys will still respond and the user can make additional menu selections.
- The command line will be accessible for appending until ENTER is pressed.
- Pressing ENTER will start the boot sequence.
Change Boot Options Temporarily For An Existing Installation
- These instructions only apply to installations that use Grub - Ubuntu's default boot loader.
- For Ubuntu 9.10 (Karmic Koala), please see Grub2
As the computer boots the default action will present a Grub message with a 3 second timer. Press the ESC key when this message appears. If the menu is not displayed during boot, the user may be able to interrupt the boot process and display the menu by pressing the ESC key during the early stages of the boot process. If the computer progresses past this point, on many computers the boot process can be restarted by simultaneously pressing CTRL-ALT-DELETE. Pressing ESC will stop the boot process and bring up the Grub menu. A fresh Ubuntu installation will normally display the current kernel, a recovery mode option, and a Memtest86+ option: Choose which kernel you want to work with. If you don't know which one, choose the first line. Press the e key to edit the line, and you will be presented with a screen like this: Then you will be presented with a screen with various lines. Use your down arrow key to highlight the "kernel" line. Press the e key to edit the kernel line. You will be presented with a screen like this: Then add or subtract whichever boot option you wish (in the above screenshot, vga=771 was added). A list of Common|Boot Options which can be added to the command lines is presented later on this page. This section is subdivided into options which can be entered on the kernel or initrd line. Press the ENTER key when you are done with the changes. Press the b key to boot the machine with the boot options you selected.
Change Boot Options Permanently On An Existing Installation
- These instructions only apply to systems that use Grub - Ubuntu's default boot loader.
- For Ubuntu 9.10 (Karmic Koala), please see Grub2
In order to permanently change your boot options, you'll need to edit the /boot/grub/menu.lst file. Before you begin, open a terminal window and type this command to back up the file with a copy that has the current date and time appended to its name:
sudo cp /boot/grub/menu.lst /boot/grub/menu.lst.`date +~%b-%d-%Y~%T`
If the system or /boot partition has changed and the user suspects the partition is not correctly identified by Grub, run this command to obtain a list of partition UUIDs. Note the system or /boot UUID and compare it to the entry on the kernel's UUID line once the kernel menu is opened:
Type this command to edit the menu.lst file:
sudo nano /boot/grub/menu.lst
(You can edit this file with any text editor, doesn't have to be nano) Use your arrow keys to move your cursor to the line that starts with "# kopt=". Add or subtract whichever boot option(s) you'd like to add to the end of the boot command, with a space between each one. Save the file.
- For nano:
- Press the Ctrl and o (this is the letter o) keys at the same time. Verify that the filename is correct (edit the filename if it's not) and press the ENTER key to save the file.
- Press the Ctrl and x keys at the same time to exit the editor.
Type this command to update the menu entries in the system:
The command may present a message indicating that a new configuration file available: "Do you want to keep the existing one for menu.lst". Select Use Package Version. If you select to keep the user modified version, your changes to kopt won't be applied to existing boot options.
Note: If you edit the menu entries directly from Grub and not with a text editor your changes will disappear the next time
update-grub is run, for instance or when the kernel or grub packages are updated.
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.
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
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.
|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.|
|nosplash||Disables splash screen.|
|text OR -s OR s OR S OR Single||Disables gdm.|
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/*.
|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.
|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.)