It is a mmu problem. If I skip disable_mmu in crt0.s run/log completes successfully. Not sure why this happens. That is probably why it crashed in Board constructor
This is the contents of sctlr_el2 0000000030c51835 ( starting at EL2 now) I provoke a crash, branch to 0x0, after mrs, and the register dump gives that value in x8.
Starting with EL3 gives the same symptom.
/Michael