In imx6dl board uboot version is 2009, fastboot flash bootloader u-boot.bin to the emmc, but can't boot up!!
MMC write: dev # 3, block # 16384, count 8688 ... 8688 blocks write: OK
Writing 'boot' DONE!
resetting ... //////////hanging here!!!
U-Boot 2009.08-dirty (Sep 28 2015 - 18:58:32)