Ethernet

Allwinner's A10 and F20 SoCs include a MAC unit called WEMAC but it's available on very few devices, most notably the Mele A1000, A2000 and A100 HTPC and the cubieboard. Due to driver similarities it's believed to be based on DM9000.

MAC
By default the WEMAC driver uses a random MAC address but it can be fixed in three different ways.

Using user-space commands like: ifconfig eth0 hw ether XX:XX:XX:XX:XX:XX using the bootloader to append mac_addr=XX:XX:XX:XX:XX:XX and the Allwinner way, adding the value to your script.bin [dynamic] MAC = "XXXXXXXXXXXX"