What worries me is the situation which I've been working on, where
we want access to the PCS PHYs, and we can't have the PCS PHYs
represented as a phylib PHY because we may have a copper PHY behind
the PCS PHY, and we want to be talking to the copper PHY in the
first instance (the PCS PHY effectivel ybecomes a slave to the
copper PHY.)

I guess we need to clarify what KR actually means. If we have a
backplane with a MAC on each end, i think modelling it as a PHY could
work.

If however, we have a MAC connected to a backplane, and on the end of
the backplane is a traditional PHY, or an SFP cage, we have problems.
As your point out, we cannot have two PHYs in a chain for one MAC.

But i agree with Russell. We need a general solution of how we deal
with PCSs.

   Andrew