uml_to_phys
#define __pa(virt) uml_to_phys((void *) (unsigned long) (virt))
init_data.stub_code_fd = phys_mapping(uml_to_phys(__syscall_stub_start),
init_data.stub_data_fd = phys_mapping(uml_to_phys(tramp_data->stub_data),