It is a Pi 2, actual Raspbian Jessi (I do update, upgrade+dist-upgrade almost daily).
Audio through hdmi, mouse microsoft wireless with its own stick and a bt-stick for my bt-keyboard. Joypad -> usb + a wifi-stick. Everything else works fine, except this message. Memorysplit is actually 256.

I first recognized this after I’ve done a complete binary install (3.5) over my ‘old’ Retropie-install (3.2?, not sure).

Days ago (as described in another thread) I removed Retropie with the new uninstall-option through the setup-script completely. After that I reinstalled it manually, only partial (ES, RetroArch, ScummVM and lrSnes9x) – without change regarding that message.