[NikolaeVarius]

That isn't the original point. The PS4 is not natively backward compatible, the base game needs to be ported.

Native BC would be

1. It runs native hardware (PS2 EE on Early PS3) 2. It runs without updates required (PS2 running inside emulator on later PS3)

This requires actual updates by the dev for individual games to work

[monocasa]

Or it's _really_ close, but the systems are complex enough that they feel they need to QA/cert the games again even if the vast majority of games require no changes.

[chungus_khan]

Do shaders on PS4 games ship precompiled? If so, they'll at least need to either recompile those or create some sort of translator (which certainly isn't impossible). Either way, I'm sure even in an ideal situation, Sony wouldn't want to make outlandishly absolute claims like "perfect backwards-compatibility".