Boot process

Boot process (pre-graphical target)

The boot process is identical to how Arch Linux boots, for one slight exception.

Due to chaotic nature of immutable Linux distribuitons, and how /etc is being handled by systemd, HoloISO implements holoiso systemd hook, which mounts /var and respective overlay for /etc on /var/overlays/etc/{upper,work} before systemd starts in order to make sure that user-added drop-ins are completely functional without unsealing RO state. If you're interested to know how it works, refer to here:

• /usr/lib/initcpio/install/holoiso
• /usr/lib/initcpio/hooks/holoiso

Boot process (post-graphical target)

By default HoloISO does the same thing as Steam Deck does, Starts SDDM, loads in gamescope-wayland.desktop as set in (var/overlays/etc/upper)/etc/sddm.conf.d/autologin.conf. However, that can be altered by using steamos-session-select to boot into: plasma, plasma-x11-persistent, gamescope in current session/next reboot.