Difference between revisions of "Kernel parameters"
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[[Category:Kernel]] | [[Category:Kernel]] | ||
− | There are three ways to pass options to the kernel and thus control its | + | [[es:Kernel parameters]] |
− | + | [[ja:Kernel parameters]] | |
− | + | [[zh-CN:Kernel parameters]] | |
− | + | There are three ways to pass options to the kernel and thus control its behaviour: | |
− | This page | + | # When building the kernel. |
+ | # When starting the kernel (usually, when invoked from a boot loader). | ||
+ | # At runtime (through the files in {{ic|/proc}} and {{ic|/sys}}). | ||
+ | |||
+ | This page now explains in more detail the second method and shows a list of most used kernel parameters in Arch Linux. | ||
== Configuration == | == Configuration == | ||
− | |||
− | ==== [[ | + | Kernel parameters can be set either temporarily by editing the boot menu when it shows up, or by modifying the boot loader's configuration file. |
− | Edit | + | |
− | {{ | + | Here we are adding the parameters {{ic|quiet}} and {{ic|splash}} to [[Syslinux]], [[GRUB]], [[GRUB Legacy]] and [[LILO]]. |
+ | |||
+ | ==== Syslinux ==== | ||
+ | |||
+ | * Press {{Keypress|Tab}} when the menu shows up and add them at the end of the string: | ||
+ | |||
+ | : {{bc|1=> .linux ../vmlinuz-linux root=/dev/sda3 ro initrd=../initramfs-linux.img ''quiet splash''}} | ||
+ | |||
+ | : Press {{Keypress|Enter}} to boot with these parameters. | ||
+ | |||
+ | * To make the change persistent after reboot, edit {{ic|/boot/syslinux/syslinux.cfg}} and add them to the {{ic|APPEND}} line: | ||
+ | |||
+ | : {{bc|1=APPEND root=/dev/sda3 ro ''quiet splash''}} | ||
+ | |||
+ | For more information on configuring Syslinux, see the [[Syslinux]] article. | ||
+ | |||
+ | ==== GRUB ==== | ||
+ | |||
+ | * Press {{Keypress|e}} when the menu shows up and add them on the {{ic|linux}} line: | ||
+ | |||
+ | : {{bc|1=linux /boot/vmlinuz-linux root=UUID=978e3e81-8048-4ae1-8a06-aa727458e8ff ro ''quiet splash''}} | ||
+ | |||
+ | : Press {{Keypress|b}} to boot with these parameters. | ||
+ | |||
+ | * To make the change persistent after reboot, while you ''could'' manually edit {{ic|/boot/grub/grub.cfg}} with the exact line from above, for beginners it's recommended to: | ||
+ | |||
+ | :Edit {{ic|/etc/default/grub}} and append your kernel options to the {{ic|GRUB_CMDLINE_LINUX_DEFAULT}} line: | ||
+ | |||
+ | :: {{bc|1=GRUB_CMDLINE_LINUX_DEFAULT="''quiet splash''"}} | ||
+ | |||
+ | :And then automatically re-generate the {{ic|grub.cfg}} file with: | ||
+ | |||
+ | :: {{bc|# grub-mkconfig -o /boot/grub/grub.cfg}} | ||
+ | |||
+ | For more information on configuring GRUB, see the [[GRUB]] article. | ||
+ | |||
+ | ==== GRUB Legacy ==== | ||
+ | |||
+ | * Press {{Keypress|e}} when the menu shows up and add them on the {{ic|kernel}} line: | ||
+ | |||
+ | : {{bc|1=kernel /boot/vmlinuz-linux root=/dev/sda3 ro ''quiet splash''}} | ||
− | + | : Press {{Keypress|b}} to boot with these parameters. | |
− | |||
− | + | * To make the change persistent after reboot, edit {{ic|/boot/grub/menu.lst}} and add them to the {{ic|kernel}} line, exactly like above. | |
− | {{ | ||
− | |||
− | + | For more information on configuring GRUB Legacy, see the [[GRUB Legacy]] article. | |
− | |||
− | |||
− | |||
− | ==== | + | ==== LILO ==== |
− | {{ | + | |
+ | * Add them to {{ic|/etc/lilo.conf}}: | ||
+ | |||
+ | : {{bc|<nowiki> | ||
image=/boot/vmlinuz-linux | image=/boot/vmlinuz-linux | ||
− | + | ... | |
− | quiet splash}} | + | </nowiki>''quiet splash''}} |
− | + | For more information on configuring LILO, see the [[LILO]] article. | |
− | |||
− | |||
== Parameters list == | == Parameters list == | ||
+ | |||
+ | {{Expansion|The list needs more parameters.}} | ||
+ | |||
{{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.}} | {{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.}} | ||
+ | |||
+ | {| border="1" | ||
+ | ![[SysVinit]]!![[systemd]]!!Description | ||
+ | |- | ||
+ | | {{ic|3}} || {{ic|1=systemd.unit=multi-user}} || Boot to a specified runlevel (3, in this case). Works with 1-6. | ||
+ | |- | ||
+ | | {{ic|1}} || {{ic|1=systemd.unit=rescue}} || Boot to Single-user mode (root). | ||
+ | |- | ||
+ | | {{ic|nomodeset}} || {{ic|nomodeset}} || Disable [[Kernel Mode Setting]]. | ||
+ | |- | ||
+ | | {{ic|1=loglevel=3}} || {{ic|1=loglevel=3}} || Removes "misaligned reg" and "unknown connector type" messages during boot with the [[Nouveau]] driver. See [https://bbs.archlinux.org/viewtopic.php?id=137509 this] topic. | ||
+ | |- | ||
+ | | -- || {{ic|1=init=/usr/lib/systemd/systemd}} || Boot using [[Systemd#Installation|systemd]] instead of SysVinit. | ||
+ | |- | ||
+ | | {{ic|1=init=/bin/sh rw}} || {{ic|1=init=/bin/sh rw}} || Boot to Shell. | ||
+ | |||
+ | |} | ||
All of these parameters are case-sensitive. | All of these parameters are case-sensitive. | ||
− | + | ||
+ | For a complete list of all known options, please see the [https://www.kernel.org/doc/Documentation/kernel-parameters.txt kernel documentation]. | ||
== See Also == | == See Also == | ||
− | * [ | + | |
− | * [http://files.kroah.com/lkn/lkn_pdf/ch09.pdf List of kernel | + | * [[sysctl]] |
+ | * [http://files.kroah.com/lkn/lkn_pdf/ch09.pdf List of kernel parameters with further explanation and grouped by similar options] |
Revision as of 19:53, 4 December 2012
zh-CN:Kernel parameters There are three ways to pass options to the kernel and thus control its behaviour:
- 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.
Contents
Configuration
Kernel parameters can be set either temporarily by editing the boot menu when it shows up, or by modifying the boot loader's configuration file.
Here we are adding the parameters quiet
and splash
to Syslinux, GRUB, GRUB Legacy and LILO.
Syslinux
- Press Template:Keypress when the menu shows up and add them at the end of the string:
-
> .linux ../vmlinuz-linux root=/dev/sda3 ro initrd=../initramfs-linux.img quiet splash
- Press Template:Keypress to boot with these parameters.
- To make the change persistent after reboot, edit
/boot/syslinux/syslinux.cfg
and add them to theAPPEND
line:
-
APPEND root=/dev/sda3 ro quiet splash
For more information on configuring Syslinux, see the Syslinux article.
GRUB
- Press Template:Keypress when the menu shows up and add them on the
linux
line:
-
linux /boot/vmlinuz-linux root=UUID=978e3e81-8048-4ae1-8a06-aa727458e8ff ro quiet splash
- Press Template:Keypress to boot with these parameters.
- To make the change persistent after reboot, while you could manually edit
/boot/grub/grub.cfg
with the exact line from above, for beginners it's recommended to:
- Edit
/etc/default/grub
and append your kernel options to theGRUB_CMDLINE_LINUX_DEFAULT
line:
-
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
-
- And then automatically re-generate the
grub.cfg
file with:
-
# grub-mkconfig -o /boot/grub/grub.cfg
-
For more information on configuring GRUB, see the GRUB article.
GRUB Legacy
- Press Template:Keypress when the menu shows up and add them on the
kernel
line:
-
kernel /boot/vmlinuz-linux root=/dev/sda3 ro quiet splash
- Press Template:Keypress to boot with these parameters.
- To make the change persistent after reboot, edit
/boot/grub/menu.lst
and add them to thekernel
line, exactly like above.
For more information on configuring GRUB Legacy, see the GRUB Legacy article.
LILO
- Add them to
/etc/lilo.conf
:
-
image=/boot/vmlinuz-linux ... quiet splash
For more information on configuring LILO, see the LILO article.
Parameters list
SysVinit | systemd | Description |
---|---|---|
3 |
systemd.unit=multi-user |
Boot to a specified runlevel (3, in this case). Works with 1-6. |
1 |
systemd.unit=rescue |
Boot to Single-user mode (root). |
nomodeset |
nomodeset |
Disable Kernel Mode Setting. |
loglevel=3 |
loglevel=3 |
Removes "misaligned reg" and "unknown connector type" messages during boot with the Nouveau driver. See this topic. |
-- | init=/usr/lib/systemd/systemd |
Boot using systemd instead of SysVinit. |
init=/bin/sh rw |
init=/bin/sh rw |
Boot to Shell. |
All of these parameters are case-sensitive.
For a complete list of all known options, please see the kernel documentation.