xs_join
watch_path = xs_join(xenbus_get_node(xbb->dev), "physical-device-path");
path = xs_join(dir, node);
path = xs_join(dir, node);
path = xs_join(dir, node);
path = xs_join(dir, node);
path = xs_join(dir, node);
root_path_sbuf = xs_join(base, node);
cur_path_sbuf = xs_join(base, node);
push_dir = xs_join(cur_path, dir[i]);
vm_path = xs_join(type, vm);
id = xs_join(vm, dev_num);
struct sbuf *xs_join(const char *, const char *);