I have enabled Secure Boot on an embedded device successfully. The problem is that when I am booting in this mode the process seems to get stuck right after the line:Starting kernel ...once U-boot has copied the kernel in memory and issued a bootm command. In a debugger I am able to capture that the PC is stuck on a yield instruction followed by an assignment to pc = pc-4 -- so essentially a loop. I have never brought up linux at this low of a level before so I am unsure where to begin looking. I did notice, though, that I was able to successfully boot the kernel image when not in secure mode, so this might be a more appropriate questions for the vendor. 1) In general, where can I find U-boot diagnostic information regarding the execution hand-off stage? 2) At what point is execution fully given to the kernel? i.e. when is U-boot defunct? 
Linux kernel hangs at Starting kernel ...
boot;linux kernel;embedded;arm;u boot