Building with devfs fails because of an error in fs/devfs/base.c:
in function is_devfsd_or_child(), the conditional code should be
erased or commented away because RH kernel already includes
the patch which removes the p_opptr field from task_struct.
The bug is still present in 2.4.20-8 shipped with RedHat 9.
devfs doesn't work in RHL and is turned off as a result.