See the top level README file for more information on documentation and how to run these programs. Sounds like this happened a while ago now, months, so I am just catching up so they have provided a way to allow for 64 bit kernels without having to load from zero and manage the cores and switching modes. So what they are saying is it looks for the file kernel8.img then kernel8-32.img then kernel7.img and last kernel.img and in that order whichever it finds is the one it uses. So with only a current bootcode.bin, start.elf and one or all of the files built here on the flash whichever it finds in that order it uses, so you can put all four .img files and it uses kernel8.img then delete that one and then it uses kernel8-32.img and so on. Yes you have to do the sd card dance. So the output is below, interesting that in 64 bit mode either my code to read the pc is wrong or they are starting at 0x80000 instead of 0x8000. There are no doubt other registers I could dump (note as this time I didnt do the work to read the CPSR in 64 bit mode so it is just zero) to see if there are any actual differences between the kernel8-32.img and kernel7.img and kernel.img as far as how it loads, etc. I guess I (you, we) could just dump the 0x0000 code they place to see if it varies. kernel8.img 12345678 00000800 00080264 00000000 12345678 kernel8-32.img 12345678 00008320 00008224 200001DA 12345678 kernel7.img 12345678 00000700 00008224 200001DA 12345678 kernel.img 12345678 00000000 00008224 200001DA 12345678