Generic Media Independent Interface device support

modulename: mii.ko

configname: CONFIG_MII

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet (10 or 100Mbit)
└─>Generic Media Independent Interface device support
In linux kernel since version 2.6.12  
Most ethernet controllers have MII transceiver either as an external
or internal device. It is safe to say Y or M here even if your
ethernet card lack MII.

source code:
drivers/net/mii.c