PlayStation 4 system software based on FreeBSD
The PlayStation 4 system software is the updatable firmware and operating system of the PlayStation 4. The operating system is Orbis OS, based on FreeBSD 9.Technology
System
The native operating system of the PlayStation 4 is Orbis OS, which is a fork of FreeBSD version 9.0 which was released on January 12, 2012.The PlayStation 4 features two graphics APIs, a low-level API named Gnm and a high-level API named Gnmx.
Most developers start with Gnmx, which wraps around Gnm, and in turn manages the more esoteric GPU details. 
This can be a familiar way to work if the developers are used to platforms like Direct3D 12.
Another key area of the game is its programmable pixel shaders. Sony's own PlayStation Shader Language (PSSL) was introduced to the PlayStation 4.It has been suggested that the PlayStation Shader Language is very similar to the HLSL standard in DirectX 12, with just subtle differences that could be eliminated mostly through preprocessor macros.Besides the kernel and related components, other components included and worth mentioning are Cairo, jQuery, Lua, Mono, OpenSSL, WebKit, and the Pixman rendering library.
Many of these are open-source software, although the PlayStation 4 is not an open console.The Software Development Kit (SDK) is based on LLVM and Clang, which Sony has chosen due to its conformant C and C++ front-ends, C++11 support, compiler optimization and diagnostics.