CONFIG_MDIO_BUS (not configurable)

configname: CONFIG_MDIO_BUS

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>MDIO_BUS
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This internal symbol is used for link time dependencies and it
reflects whether the mdio_bus/mdio_device code is built as a
loadable module or built-in.