> 
> So my question is - where exactly does the MSCP protocol fit?  Is it a
> protocol used to communicate to the controller, or is it a software access
> layer which provides a common API to the driver subsystem?  If I have any
> MSCP compliant board, would it automatically work if NetBSD supports MSCP
> boards?
> 
Yes, it should "just work". MSCP specifies a protocol that is used
to talk with controllers via descriptor rings, so it is specified
on software level. And yes, it provides a common API to the drivers.

-- Ragge