Sony PlayStation 4 runs a modified version of FreeBSD 9
The operating system on the Sony PlayStation 4 that ensures all hardware and software work in tandem is in fact a modified version of FreeBSD 9.
Sony announced that the light-weight OS running under the hood of their next-generation PlayStation 4 gaming console is in fact a modified version of FreeBSD 9. The PS4 uses the OpenGL standard for gaming while Microsoft uses its own proprietary DirectX running on a modified version of Windows (on the Xbox One of course).
What surprises Open Source experts over at Phoronix is Sony’s choice to go with FreeBSD over many other distros. This is because FreeBSD doesn’t have a supporting AMD Catalyst driver, neither do the Gallium 3D or Radeon KMS drivers fully support it. It is most likely that AMD has developed the PS4 graphics drivers from the ground up for FreeBSD, or ported the Catalyst Drivers over.
This info comes from a second-generation development kit of the PlayStation 4 console, hence it is entirely likely that the same OS will make it to the final console as well.