[U-Boot] u-boot can boot Linux in zImage format while not in uImage format

[Bo Shen]

Hi All,
   I am meeting a strange issue. The u-boot can boot device tree 
supported Linux in zImage format and can not boot in uImage format. The 
detail information as following:

   1. set the bootargs
   2. tftp 0x21000000 dtb, and tftp 0x22000000 uImage, then bootm 
0x22000000 - 0x21000000, it can not boot up. Stop at "Starting kernel..."
   3. tftp 0x21000000 dtb, and tftp 0x22000000 zImage, then bootz 
0x22000000 - 0x21000000, it boot successfully.

   I check the memory usage, no overlap. I try other memory address, 
won't fix. I check all parameters pass to kernel is right.

   Any possible reason will cause this issue?

Best Regards,
Bo Shen