fdt_gpa
error = fdt_init(ctx, guest_ncpus, fdt_gpa(ctx), FDT_SIZE);
error = vm_set_register(bsp, VM_REG_GUEST_X0, fdt_gpa(ctx));
vm_paddr_t fdt_gpa;
fdt_gpa = vm_get_highmem_base(ctx) + roundup2(len, FDT_DTB_ALIGN);
error = fdt_init(ctx, guest_ncpus, fdt_gpa, FDT_SIZE, isa);
error = vm_set_register(bsp, VM_REG_GUEST_A1, fdt_gpa);