evm.c

const char main_a_label[] = "main-A";
/* boot_mode should be "main-A" */
	if (mmc_get_dev(0) != 0)
		logical_mmc_dev = 1; // SD card present, prepare to boot from eMMC
...
	part_num = get_partition_num(boot_mode);
...
  	if (sprintf(root, "/dev/mmcblk%dp%d", logical_mmc_dev, part_num) < 0) {
  		return;
  	}