I believe that's correct, yes. Maybe an exception for fs(?) for "thread local storage"(?). I'm currently still running a 2.4 kernel, which doesn't know about that, but I think I recall reading something about it. I think it was originally gs, but changed to fs(?). In any case, "normally" we can forget that segment registers exist (with great relief!). Get back to us if you run into any trouble with that assumption.
Best,
Frank