Immutability (abroot)

abroot is a utility that provides complete immutability and atomicity by making transactions between 2 root partitions (A⟺B), it also allows for on-demand transactions via a transactional shell.

How it works

The Linux file system is a hierarchical file structure containing root and other directories. Root is the primary hierarchical directory containing all other partitions. In immutable file systems, the root partition is read-only, preventing the installation of essential packages, such as drivers in the host.

abroot allows you to install kernel modules, drivers and other essential packages without compromising the filesystem’s immutability.

When a command gets executed in abroot, a transaction gets started in the transactional shell in the second root partition. If the transaction succeeds, the changes are applied using an overlay and synced with the current root on reboot. If the transaction fails, no changes are applied (due to a property known as atomicity). abroot also allows for on-demand transactions using the abroot shell command.

Vanilla OS installations create root and boot partitions for both states (20GB per root partition) as it is a requirement for abroot.


abroot has two states - present and future. When you are in your Vanilla OS installation for the first time, the present state is A. When you reboot your system, the state automatically switches to B. When you install a package using abroot, it gets installed in the future root partition and synced with the current root partition upon reboot.


abroot powers the vso utility allowing for smart automatic updates and installation of updates in the background in the future root partition, thus saving time as an offline update during reboot isn’t required.

Kernel parameters

abroot allows setting custom kernel parameters in case a driver or custom setup requires it. By default, abroot reads the contents of /etc/default/abroot_kargs, which must not be edited. Instead, you should use the provided command to manage your parameters:

sudo abroot kargs edit

The command above will open the parameters file in your default command-line text editor (nano by default), but you can override it by using the $EDITOR environment variable before the command. So, for example, if you want to edit the arguments using vim, you can run sudo EDITOR=vim abroot kargs edit.

Kernel parameters must be separated by spaces and should not have line breaks between them. Furthermore, you should not remove the default parameters unless you know what you’re doing, as changing them could make your system unbootable.

NOTE: The kernel parameters are applied only to your future root, so you can always enter the previous root in case something goes wrong.


ABRoot’s name refers to the two transacting root partitions A and B (A⟺B).