Yep the proprietary bootloader on the Raspberry Pi handles most initialisation leaving the SoC in a usable state. If you want to see how things like DRAM init w

Yep the proprietary bootloader on the Raspberry Pi handles most initialisation leaving the SoC in a usable state. If you want to see how things like DRAM init work you can take a look at the open source reverse engineered firmware at https://github.com/christinaa/rpi-open-firmware https://github.com/christinaa/rpi-open-firmware . It isn't complete but it is just about enough to also boot the Linux kernel.