Yo guys, I've finally found out how to build RetroArch cores easily, there's an easy guide here, I've been able to build fbneo, mupen64 & race, tho some cores won't build, some like ppsspp, paralleln64 or desmume, if anyone is more familiar than I am with building those stuff, I'd be very glad to have informations to build them
Edit: while mupen64 is succesfully built, RetroArch fails to open the core, but the same error appears with cores from the AUR like redream or melonDS... Dunno what could be the cause...
Edit2: It seems the cause of the core not laoding is because the pbpro's GPU isn't supported for OpenGL, I compiled a version with GLES2 enabled because GLES3 isn't supported either, and the sound is botchy but it can run some games like mario kart 64, F-Zero, Paper Mario & Mario 64 if you're not very demanding on sound quality...