GRUB/Configuration variables
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This article provides a reference of the variables that may be set in /etc/default/grub to control the configuration file generated by grub2-mkconfig.
General
| Variable | Default | Description |
|---|---|---|
| GRUB_DEFAULT | 0 | Default menu entry selected on boot. The entry may be identified by number (starting from 0), title, or id. When using submenus, it is specified by menu>submenu, like 0>1, or other>minix>minix-3.4.0 (see documentation on grub default variable or this post on gentoo-forums). |
| GRUB_TIMEOUT | 5 | Delay before booting default menu entry. Set to 0 to boot immediately or -1 to wait indefinitely.
|
| GRUB_DEVICE | (detected) | Device node for the volume containing the root filesystem. Set this to override the grub2-mkconfig command's root device auto-detection. For example, GRUB_DEVICE=/dev/ram0 will force root=/dev/ram0 to be used in the kernel command line.
|
| GRUB_DEVICE_UUID | (detected) | UUID of the root filesystem. |
| GRUB_DISABLE_RECOVERY | false | If true, recovery menu entries will not be generated. On Linux, recovery entries pass "single" on the kernel command-line. |
| GRUB_FONT | (detected) | Font in pf2 format used during gfxmode display. Not setting one can prevent gfxmode. pf2 fonts can be created using the grub2-mkfont utility. For example, to create a GRUB2 fp2 font from a TTF (True Text Font) called DroidSansMonoSlash.ttf run: root #grub2-mkfont /usr/share/fonts/droid/DroidSansMonoSlashed.ttf --size=20 --output /boot/grub/fonts/DroidSansMonoSlashed20.pcfTo use the newly created font, set the GRUB_FONT variable to the font's location. CODE Example GRUB_FONT configuration GRUB_FONT=/boot/grub/fonts/DroidSansMonoSlashed20.pcf
|
| GRUB_DISABLE_OS_PROBER | true | When true, the os-prober utility is bypassed meaning additional OS loaders will not be searched. Setting GRUB_DISABLE_OS_PROBER=false will have grub-mkconfig search for additional installations when os-prober is installed.
|
| GRUB_PRELOAD_MODULES | List of GRUB module names separated by spaces that will be loaded at the start of grub.cfg. This may be needed if the GRUB boot is in a LVM partition. |
Linux
| Variable | Default | Description |
|---|---|---|
| GRUB_CMDLINE_LINUX | Extra parameters to be passed on the kernel command line for all Linux menu entries. For instance, to support hibernation, users will need to add GRUB_CMDLINE_LINUX="resume=/dev/sdXY" with /dev/sdXY being the swap partition.
| |
| GRUB_CMDLINE_LINUX_DEFAULT | Extra parameters to be passed on the kernel command line for non-recovery Linux menu entries. | |
| GRUB_DISABLE_LINUX_UUID | false | If true, ${GRUB_DEVICE} is passed in the root parameter on the kernel command line.
If false, |
| GRUB_DISABLE_LINUX_PARTUUID | true | Since version 2.04. If false, and if there is either no initramfs or GRUB_DISABLE_LINUX_UUID is set to true, ${GRUB_DEVICE_PARTUUID} is passed in the root parameter on the kernel command line. See Root identification Heuristics.
|
| GRUB_GFXPAYLOAD_LINUX | text | Controls the video mode in which the Linux kernel starts. May be set to "text", "keep", or a display resolution. |
Xen
| Variable | Default | Description |
|---|---|---|
| GRUB_CMDLINE_XEN | Extra parameters to be passed on the Xen command line for all Xen menu entries. For instance, to have a timestamped Xen dmesg, users will need to add GRUB_CMDLINE_XEN="console_timestamps=boot".
| |
| GRUB_CMDLINE_XEN_DEFAULT | Extra parameters to be passed on the Xen command line for non-recovery Xen menu entries. | |
| GRUB_CMDLINE_LINUX_XEN_REPLACE | Overrides the GRUB_CMDLINE_LINUX variable from the above Linux section for Xen boot lines only. | |
| GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT | Overrides the GRUB_CMDLINE_LINUX_DEFAULT variable from the above Linux section for Xen boot lines only. Users may prefer to start a specific softlevel for xen via GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT="softlevel=xen"
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