sd-hold blocks the boot process so that the system remains in the initramfs phase. This can be used to perform all kinds of actions during the initramfs phase. (E.g., you may want to perform some action on your root file system (backup, restore, encryption, ...) without a running system already using this root file system.) Only when you (or some other mechanism) deletes the file /etc/hold the boot process continues.

Mind that some access to the preliminary linux system during the initramfs phase is required. Otherwise you will not be able to delete /etc/hold and the boot process will be blocked forever. Options are

• Include TinySSH server or Dropbear SSH server into your initramfs image (together with networking).

• Enable console access. (To be evaluated.)

Add sd-hold to the array HOOKS in /etc/mkinitcpio.conf. The entry must be positioned somewhere after (right of) systemd. Apart from that the concrete position is irrelevant. No further configuration is required.