Booster

Booster is a fast initramfs generator similar to mkinitcpio and dracut. Booster is inspired by distri project and aims to create a small and fast init image.

Booster consists of two major components:

Initramfs generator /usr/bin/booster user-space tool. It is responsible for initramfs image generation.
Generated images that are usually located at /boot/ and used by the system boot loader to boot Linux OS.

Install

Install booster. The package installation hook will generate initramfs images, one per installed kernel (e.g. for , ). The images are located under /boot directory:

Or the image can be built manually:

$ booster build mybooster.img

Configuration

Booster generator configuration is located at /etc/booster.yaml. If there is no configuration file then the default configuration (host-specific images, no network) is used.

The configuration file helps to override the default behaviour. See for detailed information.

Regenerate booster images

Once you are done with booster configuration you need to update booster images at /boot. An image can be generated manually with or using a convenience script that iterates over all installed kernels and generates booster image for each of them.

Boot loader configuration

Once the image is generated it is time to configure the boot loader.

rEFInd

If the configuration relies on automatic detection already, no additional configuration change is necessary. rEFInd supports initrd files named booster*.

If you specify the initramfs path manually, either in refind.conf or in manual boot stanzas, make sure to use the correct files names. I.e. instead of .

systemd-boot

To enable the new initramfs image with systemd-boot simply create a new boot loader entry like this one:

Where the root filesystem is referenced by . To find your root device UUID run .

Enable encryption

Booster supports LUKS based full disk encryption out of the box and Clevis too. Generator does not need any extra configuration. And for initramfs you need to append information about the LUKS partition where the root resides. This is done with either or rd.luks.name=LUKSUUID=LUKSNAME kernel parameter that you need to specify in your boot loader configuration file. LUKSUUID specifies UUID of the encrypted LUKS partition that needs to be unlocked by booster. Pay attention that the UUID does not contain any quotes. specifies name of the unlocked partition (as in ).

No image rebuild is required. Once the boot loader configuration is done, reboot the computer. After that you will see a prompt at the boot time asking for a password for the encrypted root partition.

Systemd style binding

Booster also supports partitions bound with systemd such as and .

If you use `systemd-fido2` then please install package and add fido2-assert to the image using following configuration:

Regenerate the booster images. Booster will detect this configuration during boot and use the present YubiKey to unlock the drive.

Debug

If booster has issues and does not work as expected then please enable debug output that provides extra information about what is going on:

for generator there is a command line flag: .
for init there is a booster.debug kernel parameter.

If you believe it is an issue with booster itself then please file a ticket here https://github.com/anatol/booster/issues

Gotchas

Early module loading

The are situations when some kernel modules need to be loaded early, at initramfs stage.

For example, if you need to load the nvidia module, then use the following configuration setting:

And then regenerate booster images.

Booster generator fails with "too many open files" error

If you enabled and and see an error like , then you need to increase per-process limit for open files. See Limits.conf#nofile.