I'm trying to compile the kernel to make my BCM4322 wireless card work on my laptop that's become a server, and these files are giving me trouble... If you look at the source tree, miidevs has been updated on its own in the past months, while the other files are years old. sys/dev/mii/miidevs is missing its extension, and it has a $FreeBSD$ header... I'm trying to recompile without it from GENERIC only adding what I need, but that file was giving me a lot of trouble... At any rate, it has the header, which causes a fatal compiler error, so someone should look into it...
Please provide relevant details. What exactly you do, what exactly you get, any local changes / configuration, etc.