subprimitives are arm64 bytes
primitives are C calls



CALLBACK-STUB jit-define gets called first
set 9999 BRK to break there in lldb
lldb ./factor
run -i=boot.unix-arm.64.image

then do c-to-factor


rel- relocations aka fixups 
rel-vm relocation for vm in sidetable

relocation addresses are 64bit
look at powerpc backend
return a 64bit value in a register