Difference between revisions of "Kernel parameters"

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| [[SystemD]]  || systemd.unit = $target || boot to $target
 
| [[SystemD]]  || systemd.unit = $target || boot to $target

Revision as of 04:57, 20 September 2012

There are three ways to pass options to the kernel and thus control its behavior:

  • When building the kernel.
  • When starting the kernel (usually, when invoked from a boot loader).
  • At runtime (through the files in /proc and /sys).

This page now explains in more detail the second method and shows a list of most used kernel parameters in Arch Linux. For a complete list of all known options, please see the kernel documentation.

Configuration

When building the kernel

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Notes: More to come... (Discuss in Talk:Kernel parameters#)

When starting the kernel

Kernel parameters can be set by modifying boot loader configuration file. You can also set them manually for current boot when the boot loader menu shows up.

Here we are adding the parameters quiet and splash to GRUB, GRUB Legacy, LILO and Syslinux.

GRUB

Edit the file /etc/default/grub and append your kernel options to the line GRUB_CMDLINE_LINUX_DEFAULT="":

/etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="ro quiet splash"

Re-generate grub.cfg with:

# grub-mkconfig -o /boot/grub/grub.cfg

The resulting line in /boot/grub/grub.cfg will look like:

/boot/grub/grub.cfg
linux	/vmlinuz-linux root=/dev/sda3 quiet splash

GRUB Legacy

For GRUB Legacy the kernel parameters go into the kernel line of menu.lst.

/boot/grub/menu.lst
kernel /vmlinuz-linux root=/dev/sda3 ro quiet splash

LILO

/etc/lilo.conf
image=/boot/vmlinuz-linux
        [...]
        quiet splash

Syslinux

/boot/syslinux/syslinux.cfg
APPEND root=UUID=988d4e11-8237-4af3-5ab6-77627128g9d0 ro vga=current quiet splash

At runtime

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Notes: More to come... (Discuss in Talk:Kernel parameters#)

Parameters list

Note: Not all of the listed options are always available. Most are associated with subsystems and work only if the kernel is configured with those subsystems built in. They also depend on the presence of the hardware they are associated with.

All of these parameters are case-sensitive.

Tango-document-new.pngThis article is a stub.Tango-document-new.png

Notes: Add more to the list. (Discuss in Talk:Kernel parameters#)
Parameter Example Description
Init 1 change to specified runlevel(1-6)
SystemD systemd.unit = $target boot to $target

You can find a list of kernel parameters here: https://www.kernel.org/doc/Documentation/kernel-parameters.txt

See Also