The value of State

[vietle77]

The value of State

[nihalpasham]

So, rustBoot uses (its own) state-ids to represent the state of a (boot/update) partition. The state-id is actually a single-byte identifier that lives at the end of boot/update partition. It looks something like this - on flash-memory

[...header...][...padding...][....firmware image....][.... free space....][...partition sector flags...][single byte partition status][4-byte trailer magic]

1. StateNew or (0xFF) means the image was never staged for boot, or triggered for an update.
2. StateUpdating or (0x70): This is only valid in the update partition. This basically means that the OS/firmware has marked an image as ready for update and should replace the current image in the boot partition on the next reboot.
3. StateTesting or (0x10): This is only valid in the boot partition. It means the image has just been updated, and is pending a reboot. If we see the same state after a reboot, it means that the updated image failed to boot, despite being correctly verified. This particular situation triggers a rollback.
4. StateSuccess (0x00): This is only valid in the boot partition. It means the new image is stored in boot has been successfully staged at least once, and the update is now complete.