A/B slot

The two read-only system partitions on a baked image — slotA and slotB. One is active; the other is the rollback target. An update writes the new image into the inactive slot, sets a one-shot boot pointer, and reboots; if the new slot fails the watchdog, the bootloader returns to the previous slot. See Operations → Update and rollback. Not every hardware target supports A/B; cloud targets use platform snapshots or re-deploy instead.