The version of uboot is 2015, and the patchlevel of uboot is 04.
I noticed that this uboot has a configure file mx6sabresd_spl_defconfig in configs/ when I was about to give it a patch, which is used to support SPL. Because I compared my patch downloaded from internet with this uboot's code, and found that they are almost the same. So I make mx6sabresd_spl_defconfig directly without appling my patch, then "dd" SPL&u-boot.img into SD card and insert SD card into SD3. The commands are:
sudo dd if=SPL of=/dev/sdc bs=1k seek=1;sync
sudo dd if=u-boot.img of=/dev/sdc bs=1k seek=69
However, there is no any printed information, and I don't know why. Can someone help me?