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Dracut

Overview

dracut is a highly modular tool for generating initramfs images.

As of the Cassini release in 2022, it is the default for EndeavourOS.

In general, it is superior to mkinitcpio in it’s ability to autodetect needed modules and for most use cases will work without any further configuration.

Regenerating the initrds

You can regenerate the initrds with the command sudo dracut-rebuild

Customizing dracut

Dracut is configured via drop-in conf files in the /etc/dracut.conf.d

Making the initramfs smaller

For example, if you wanted to limit the size of your initrd, you could add a file named smaller.conf with the contents of:

hostonly_mode=strict

Adding a dracut module

Another common item might be to add a module manually. While most modules will be automatically configured, there may be times you want to add a module.

For example, if you wanted to forcibly add support for mdraid, you could use a file with the contents of:

add_dracutmodules+=" mdraid "

It is worth noting that this is not generally needed as dracut will automatically detect when mdraid support is needed.

Removing a module

If you want to ensure that a module doesn’t get added to the initramfs image, you can do so like this:

omit_dracutmodules+=" i18n "

This would remove i18n support from the initrd. This is another way to reduce the size if you don’t need support for internationalization.

Early KMS loading

If you need early KMS loading for nvidia that can be done with a this content:

force_drivers+=" nvidia nvidia_modeset nvidia_uvm nvidia_drm "

For Intel:

force_drivers+=" i915 "

For modern AMD:

force_drivers+=" amdgpu "

Making dracut less verbose

Edit config file located at /etc/eos-dracut.conf or /etc/kernel-install-for-dracut.conf and set DRACUT_QUIET to DRACUT_QUIET="true"

This will enable dracut’s quiet mode, which will suppress most output.

Disable the generation of the fallback initrd

Edit config file located at /etc/eos-dracut.conf or /etc/kernel-install-for-dracut.conf and set NO_DRACUT_FALLBACK to NO_DRACUT_FALLBACK="true"

This will stop future fallback initrds from being generated.

Please note that this will not remove any existing fallback initrds that already exist. When using kernel-install-for-dracut (systemd-boot), this will change automatically as new kernel updates happen. For eos-dracut (grub), you will need to remove them manually.

Update (rebuild) kernel boot images

When using default systemd-boot and dracut:

sudo reinstall-kernels

When using Grub and dracut:

sudo dracut-rebuild

Converting to dracut from mkinitcpio

If you would like to convert an existing system to dracut, the process is very simple. You can use the following commands depending on if you are using systemd-boot or grub.

systemd-boot with kernel-install

If you use systemd-boot, this process is fairly simple

sudo pacman -S kernel-install-for-dracut

If you receive an error about the package mkinitcpio-openswap, uninstall it with sudo pacman -R mkinitcpio-openswap and run the command again.

If you have any LUKS encrypted file systems, you must create a dracut drop-in config for that. Create the file /etc/dracut.conf.d/encryption.conf with the following content:

install_items+=" /etc/crypttab "

If you have an encrypted swap partition, you must also add a line that looks like this to the encryption.conf file created above:

add_device+=" /dev/disk/by-uuid/ad44a367-09ec-4f74-bf66-f284438280db "

However, be sure to replace ad44a367-09ec-4f74-bf66-f284438280db with the UUID for your swap luks partition.

Last run sudo reinstall-kernels and reboot

grub (or any other bootloader)

For any other bootloader, this process should be followed.

sudo pacman -S dracut

sudo pacman -S eos-dracut

sudo pacman -Rc mkinitcpio

If you have any LUKS encrypted file systems you must create a dracut drop-in config for that. Create the file /etc/dracut.conf.d/encryption.conf with the following content:

install_items+=" /etc/crypttab /crypto_keyfile.bin "

If you have an encrypted swap partition, you must also add a line that looks like this to the encryption.conf file created above:

add_device+=" /dev/disk/by-uuid/ad44a367-09ec-4f74-bf66-f284438280db "

However, be sure to replace ad44a367-09ec-4f74-bf66-f284438280db with the UUID for your swap LUKS partition.

sudo dracut-rebuild

Optional: Install the EOS defaults for dracut

EOS ships with some custom default settings for dracut. If you would like to install these, you can do so with this command:

curl https://raw.githubusercontent.com/endeavouros-team/EndeavourOS-ISO/main/airootfs/etc/dracut.conf.d/eos-defaults.conf | sudo tee /etc/dracut.conf.d/eos-defaults.conf

These will take effect next time your initrds are regenerated.

Dracut and the bootloaders systemd-boot and grub

To mangage kernel handling related to the two bootloader options, EndeavourOS uses two helper tools:

systemd-boot uses: kernel-install-for-dracut package/tool

grub uses eos-dracut package/tool

Make sure to have the correct package tool installed to pair with the bootloader you are using.

More information

There are a few other good sources of information on dracut.

  • One of the best sources of information on dracut modules is the Gentoo wiki.
  • Likewise the Arch wiki contains some good information on dracut.
  • The official dracut wiki is also a good source of reference information.
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