12 Kernel Boot Parameter Reference

The following table describes some commonly used kernel boot parameters.

Option Description

0, 1, 2, 3, 4, 5, or 6, or systemd.unit=runlevelN.target

Specifies the nearest systemd-equivalent system-state target to match a legacy SysV run level. N can take an integer value between 0 and 6.

Systemd maps system-state targets to mimic the legacy SysV init system.

For a description of system-state targets, see Oracle Linux 8: Managing the System With systemd

1, s, S, single, or systemd.unit=rescue.target

Specifies the rescue shell. The system boots to single-user mode prompts for the root password.

3 or systemd.unit=multi-user.target

Specifies the systemd target for multiuser, nongraphical login.

5 or systemd.unit=graphical.target

Specifies the systemd target for multiuser, graphical login.

-b, emergency, or systemd.unit=emergency.target

Specifies emergency mode. The system boots to single-user mode and prompts for the root password. Fewer services are started than when in rescue mode.

KEYBOARDTYPE=kbtype

Specifies the keyboard type, which is written to /etc/sysconfig/keyboard in the initramfs.

KEYTABLE=kbtype

Specifies the keyboard layout, which is written to /etc/sysconfig/keyboard in the initramfs.

LANG=language_territory.codeset

Specifies the system language and code set, which is written to /etc/sysconfig/i18n in the initramfs.

max_loop=N

Specifies the number of loop devices (/dev/loop*) that are available for accessing files as block devices. The default and maximum values of N are 8 and 255.

nouptrack

Disables Ksplice Uptrack updates from being applied to the kernel.

quiet

Reduces debugging output.

rd_LUKS_UUID=UUID

Activates an encrypted Linux Unified Key Setup (LUKS) partition with the specified UUID.

rd_LVM_VG=vg/lv_vol

Specifies an LVM volume group and volume to be activated.

rd_NO_LUKS

Disables detection of an encrypted LUKS partition.

rhgb

Specifies to use the Red Hat graphical boot display to indicate the progress of booting.

rn_NO_DM

Disables Device-Mapper (DM) RAID detection.

rn_NO_MD

Disables Multiple Device (MD) RAID detection.

ro root=/dev/mapper/vg-lv_root

Specifies that the root file system is to be mounted read-only, and specifies the root file system by the device path of its LVM volume (where vg is the name of the volume group).

rw root=UUID=UUID

Specifies that the root (/) file system is to be mounted read-writable at boot time, and specifies the root partition by its UUID.

selinux=0

Disables SELinux and touches the /.autorelabel file so that SELinux file contexts are automatically relabeled the next time you boot with SELinux enabled.

Don't disable SELinux in production environments. Rather, set SELinux to permissive mode.

enforcing=0 Sets SELinux to permissive mode until next rebooted. In permissive mode, file contexts are automatically labeled and denials are logged, but applications can continue to function.

Use SELinux permissive mode to debug SELinux issues.

SYSFONT=font

Specifies the console font, which is written to /etc/sysconfig/i18n in the initramfs.