int __xmknod(int ver, __const char *path, __mode_t mode, __dev_t *dev);
ver must be 1 or the behavior is undefined.
__xmknod(1, path, mode, dev) has the same specification as mknod(path, mode, dev).
Note that the format of dev_t is not the same as the argument that the kernel syscall uses.
__xmknod is not in the source standard; it is only in the binary standard.