What is the difference between a Bootrom vs bootloader on ARM systems

Question

I primarily come from an x86 system background where BIOS (Firmware) is responsible for loading a bootloader (like GRUB) from PowerON which in turn loads the OS. I now have been

Answer 1

ARM CPUs can have flash ROM i.e. the chip mask includes some code to load the BIOS. A lot has been said about the GPU doing MOST of the boot sequence but I have my reservations. Does the GPU run ARM code? No. So, in the face of the official version of the boot sequence, I see from the original GPU data, 32K is copied into L2 cache (since DRAM hasn't been switched on) and from that point, the CPU runs code to load the BIOS from the SDRAM. No Trustzone settings are enabled in the boot sequence. That allows a bare-metal coder (embedded systems) to use the vast majority of the CPU FlashROM as vector tables so you can poll the Hardware and set up vectors as required. The TZ stuff has no useful properties since The Smurf Suite proves that it isn't secure. But if you use that space for vectors, if someone reflashes, the OS dies.