It doesn't run on FreeBSD, its kernel is based off FreeBSD. Really it just saves them having to re-implement TCP/IP, VFS, etc. The userland is all entirely diff

It doesn't run on FreeBSD, its kernel is based off FreeBSD. Really it just saves them having to re-implement TCP/IP, VFS, etc. The userland is all entirely different. It also uses different (custom) hardware and makes assumptions about it; no OpenGL/DirectX layer of abstraction, for example, since the hardware is fixed for the next 10 years your API call doesn't have to do different things on different hardware. You'd have to provide abstractions for all of that. Likewise for the CPU; it's possible there are CPU/GPU extensions in the PS4 that don't exist in standard commercial hardware. On top of all that, the binaries are all signed/encrypted, so without the ability to decrypt them it doesn't do us much good.