As title, what OS does RP use, I was under the impression it was Linux based?. The buildbot for main line RetroArch has recently started build cores for Linux (before it was just windows, andriod and iOS) I was really happy about this as I was under the impression these would work with RetroPie but upon copying the .so file for vbam emulator into the corect folder location on the RPi2 and setting up EmulationStation to look in the correct folder the emulator loads but the just resets back to ES. So I’m guessing vanilla Linux .So emulator files are not comparable with RetroPie??
Linux x86 != Linux ARMv6 softfloat != Linux ARMv6 hf != Linux ARMv7 hf != Android 😉
A *.so library works only on supported platforms. So if RetroArch builds cores for x86 linux with desktop OpenGL it will not work. Or if *.so supports only ARMv7 with neon and desktop OpenGL (BeagleBone should have such a build target) it will not run with your pi.
There are different Linux version for different processor architectures. Every architecture can run operating systems that are written for it. You don’t have to run Linux on an Rpi. You can also run RiscOS. And in the near future Windows 10. And maybe Android will be ported to the RPi2…. if someone wants to do that.
Retropie is Linux.
The hardware is not based on any operating system, the operating systems are written for the hardware.