- When the Raspberry Pi is first turned on, the ARM core is off, and the GPU core is on. At this point the SDRAM is disabled.
- The GPU starts executing the first stage bootloader, which is stored in ROM on the SoC. The first stage bootloader reads the SD card, and loads the second stage bootloader (bootcode.bin) into the L2 cache, and runs it.
- bootcode.bin enables SDRAM, and reads the third stage bootloader (loader.bin) from the SD card into RAM, and runs it.
- loader.bin reads the GPU firmware (start.elf).
- Not 100% sure what happens next