entries # 0 384 r 0 reserved_memory 384 4 r 0 reboot_bits # leave 3 bits to make checksummed area start byte-aligned 392 1 e 2 boot_option 400 4 e 4 debug_level # leave 7 bits to make checksummed area end byte-aligned 408 16 h 0 check_sum enumerations #