*Normal boot kernel starts&loads OS components to located in the kernel partition to point(OS can read from the system partition) At this point: nothing is located in the kernel partition until the run-time image is booted.
*Device update IPL knows where the master boot record(MBR). active partition is stored in the MBR. IPL loads the contents of active partition(kernel partition) to RAM(NAND,NOR), or jumps to startup address if the artition is NOR XIP kernel.
*during an update to the kernel partition to system partitionpackage mechanism donwloads (update packages) to (device's persistent user store)
UpdateBin- checks signature on the packages,
- validates the package contents,
- verifies versions,
- sets a flash update flag(update is available)
- rebbots the system. at reboot, IPL notes the flag and invokes ULDR.
*when ULDR is booted and runing from RAM, ULDR searches the validated packages in the user store (contains file system drivers).
begins update process one package at a time package information is recorded in the file system for useing by Update Validator on future updates. the update progress is tracked to allow for roll-forward updates in case a power failure occurs during the update.
*when all package contents have been applied and complete, the package can be removed from the user store or marked as completed. the flash update flag is cleared the device is rebooted.
