SD and MMC Device Partitions============================Device partitions are additional logical block devices present on theSD/MMC device.As of this writing, MMC boot partitions as supported and exposed as/dev/mmcblkXboot0 and /dev/mmcblkXboot1, where X is the index of theparent /dev/mmcblkX.MMC Boot Partitions===================Read and write access is provided to the two MMC boot partitions. Due tothe sensitive nature of the boot partition contents, which often storea bootloader or bootloader configuration tables crucial to booting theplatform, write access is disabled by default to reduce the chance ofaccidental bricking.To enable write access to /dev/mmcblkXbootY, disable the forced read-onlyaccess with:echo 0 > /sys/block/mmcblkXbootY/force_roTo re-enable read-only access:echo 1 > /sys/block/mmcblkXbootY/force_ro