Depends on what systems you're talking about. Forcing unused
code into the kernel is not free, especially if that's made into
a design policy and applied repeatedly to many subsystems.
Why not just fix the thing which changed and broke the build?
Or if reverse dependencies can't be made to work sanely, then
have those Ethernet-adapter minidrivers depend on NET_ETHERNET
and then select MII. (To make the relationships be simple
enough that current Kconfig can handle them.)
I have a fair number of usbnet devices. Not one of them needs
MII or NET_ETHERNET.
- Dave
-