In a recent video [Jeff Geerling] addresses an issue discovered with the Raspberry Pi firmware, specifically how since around 2024 the firmware locks down what RAM size and even module is ...
The firmware-2711 directory contains the EEPROM images for BCM2711-based products (Pi 4, Pi 400, CM4, CM4S) and firmware-2712 contains the images for BCM2712-based products (Pi 5, Pi 500, CM5).
2712: Initialise SDRAM with safe/high-temeprature refresh settings Update the SDRAM controller initialisation to start with the worst case refresh rate (for high temperatures). Later on, the SDRAM ...