The model board i used is imx28evk, and I have been finished the sd/mmc boot mode, the next step is nand flash boot mode. i have get something aboot nand boot from "imx28 applications processor reference manual", but i still do not know how to start on nand boot. Does need i to add nand drivers for u-boot, or do other jobs? Can you give me some advise or something about nand boot. Thank you very much for you help!