dracut

The --force flag overwrites the image file if it is already present.

The option specifies which kernel to use. The argument to this option must match the name of a directory present in /usr/lib/modules.

More flags can be found with .

dracut uses a modular approach to build the initramfs (see ). All of dracut 's builtin modules are located in and can be listed with dracut --list-modules. Extra modules can be provided by external packages e.g. . dracut 's built-in modules unfortunately lack documentation, although their names can be self-explanatory.

Some of the modules are active/inactive by default, and can be activated/deactivated with / command line argument or with the /omit_dracutmodules+="" persistent config entry lines.

To make use of systemd 's unlocking of luks2 encrypted volumes using TPM2 through systemd-cryptenroll, enable the dracut module.

Dracut enables early loading (at the initramfs stage, via ) through it's command or config entry line. For example:

/etc/dracut.conf.d/myflags.conf

# ...
force_drivers+=" nvidia nvidia_modeset nvidia_uvm nvidia_drm "
# ...

Kernel command line options can be placed in a .conf file in , and set via the flag. Dracut will automatically source this file and create a file and place it inside the initramfs directory . For example, your kernel command line options file could look like:

It is not necessary to specify the root block device for . From :

The root device used by the kernel is specified in the boot configuration file on the kernel command line, as always.

However, it may be useful to set some parameters early, and you can enable additional features like prompting for additional command line parameters. See for all options. Here are some example configuration options:

• Resume from a swap partition:
• Prompt for additional kernel command line parameters:
• Print informational output even if "quiet" is set: rd.info

dracut can produce unified kernel images with the command line option or with the configuration option.

You can view information about a generated initramfs image, which you may wish to view in a pager:

# lsinitrd /path/to/initramfs_or_uefi_image | less

This command will list the arguments passed to when the image was created, the list of included modules, and the list of all included files.

To reduce the amount of time spent compressing the final image, you may change the compression program used.

Simply add any one of the following lines (not multiple) to your dracut configuration:

compress="cat"
compress="gzip"
compress="bzip2"
compress="lzma"
compress="xz"
compress="lzo"
compress="lz4"
compress="zstd"

is the default compression program used.  will make the initramfs with no compression.

You can also use a non-officially-supported compression program:

compress="program"

It is possible to automatically generate new initramfs images upon each kernel upgrade. The instructions here are for the default linux kernel, but it should be easy to add extra hooks for other kernels.

As the command to figure out the kernel version is somewhat complex, it will not work by itself in a pacman hook. So create a script anywhere on your system. For this example it will be created in .

The script will also copy the new kernel file to , since the kernel packages do not place files in anymore.

/usr/local/bin/dracut-remove.sh

#!/usr/bin/env bash

while read -r line; do
	if [[ "$line" == 'usr/lib/modules/'+([^/])'/pkgbase' ]]; then
		read -r pkgbase < "/${line}"
		rm -f "/boot/vmlinuz-${pkgbase}" "/boot/initramfs-${pkgbase}.img" "/boot/initramfs-${pkgbase}-fallback.img"
	fi
done

You need to make the scripts executable. If you wish to add or remove flags, you should add them to your dracut configuration.

The next step is creating pacman hooks:

You should stop mkinitcpio from creating and removing initramfs images as well, either by removing mkinitcpio or with the following commands:

# ln -sf /dev/null /etc/pacman.d/hooks/90-mkinitcpio-install.hook
# ln -sf /dev/null /etc/pacman.d/hooks/60-mkinitcpio-remove.hook

If resuming from hibernation does not work, you may need to configure to include the module. You will need to add a configuration file:

If the kernel has issues auto discovering and mounting LVM / software RAID / LUKS blocks. You can retry generating an initramfs with the following kernel command line options:

rd.auto rd.lvm=1 rd.dm=1 rd.md=1 rd.luks=1

If you have issues booting or very long shutdown processes while the system waits for , add the following to the dracut configuration line:

omit_dracutmodules+=" brltty "

Alternatively, uninstall if it is not needed.