MBR_BS_OFFSET
copy_size = MBR_BS_OFFSET;
if (validate_bootsel((void *)((uint8_t *)boot + MBR_BS_OFFSET + 4))) {
memmove((uint8_t *)boot + MBR_BS_OFFSET,
(uint8_t *)boot + MBR_BS_OFFSET + 4,
ATF_CHECK_EQ(MBR_BS_OFFSET, offsetof(struct mbr_sector, mbr_bootsel));
uint offset = MBR_BS_OFFSET;