Using Pi4 image on Pi3

slumcat

I made a completely bone-headed mistake yesterday. The SD card on my Retropie died, so I spent the last couple days rebuilding it with the latest image. I could have sworn it was built on a Pi4 (and somehow completely overlooked the micro USB and full-sized HDMI port), so I started from the pre-built Pi4/400 image. At first boot it was acting a bit weird (EmulationStation didn’t auto-launch and I got some alsa mixer warning messages), so I did a full update from the Retropie-setup script and then went about the business of transferring all of my backed up roms, configs, etc. Everything seems to be working OK for now, but today it finally dawned on me that it’s running on a Pi3B, not a 4. What is the difference in the pre-built images for the 3 vs. 4? Is there anything I should be concerned about? Since I did a full update (including underlying OS) am I all good now, or should I start all over and rebuild with the proper image?

Thanks in advance for any help.

Pi Model or other hardware: Raspberry Pi 3 Model B Rev 1.2
Power Supply used: 5V 2.5A wall-wart
RetroPie Version Used: 4.7.20
Built From: retropie-buster-4.7.1-rpi4_400.img.gz

dankcushions

@slumcat it uses curated builds, configurations and default emulators for pi4. i am not sure what specifically will break if you use it on a pi3 system, but you'll certainly not be making optimal use of your hardware.

retropieuser555

I mean, things like redream it might try and run but it'll fail as it needs pi4?

mitu

@retropieuser555 You won't be able to install redream on a Pi3 (and it's not included in the image out-of-the-box) even if the image was intended for a Pi4.

@slumcat as @dankcushions mentioned, some configurations may not be optimal for your platform (Pi3). Doing an update will install the correct software version for your system (i.e. the Pi3 packages), but the default configurations will not be re-generated.

windg

Pi3 have a parameter in the config.txt file that does not exist in the Pi4 :

gpu_mem=256

slumcat

@mitu @dankcushions

Thanks for the info. I guess I will go ahead and rebuild it, again!