Comment # 20 on bug 1178797 from Anton Smorodskyi

(In reply to Andreas Herrmann from comment #19)
> (In reply to Franck Bui from comment #18)
> > (In reply to Andreas Herrmann from comment #17)
> > > Depends on whether the rules file is used also with
> > > an older kernel still supporting the legacy block layer.
> > > (E.g. someone installing an old kernel)
> > 
> > Well as a kernel guy, you probably know better than us ;)
> 
> Thought more about it.
> I think keeping the legacy rules (for CFQ and deadline) in there and moving
> the elevator check after blk-mq rule is the safer approach. In case someone
> boots an old kernel with legacy block layer support it works as usual.

maybe we could at least add some informational comment which would warn user
that this check make sense only till kernel version X ?