Gentlemen,
Sorry to jump in, I read the thread but I am not sure what the goal here is. However, if you are going to do PCIe boot on C6678, there are a lot of working examples here already with MCSDK:
C:\ti\mcsdk_2_01_02_06\tools\boot_loader\examples\pcie
There is a readme under docs folder. Please read it so you can re-use in stead of create your own.
best regards,
David Zhou