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If I understand VideoCore IV correctly, it contain a bootrom (and perhaps some other information in the ROM). I understand that the bootrom contain a different instruction set than ARM. I would guess it would be the same instruction set as the second and third boot loader stage (bootcode.bin/start.elf) that setup the system and load the os kernel.

  1. Is it possible to flash the VideoCore IV ROM at all?
    (Can I view an archive of firmware updates online?)
  2. Can Broadcom change the bootrom in any way?
    (Can they get rid of the dependency of having a FAT partition post-manufacture?)
    (Is firmware signed cryptographically so only Broadcom can change bootrom?)

The reason I am asking this is mostly for curiosity. I want to learn what is possible to do and not how hard it is. If you happen to have links to resources where I can learn more, the merrier. If there already are documents that explain this in depth, I've obviously not yet found them and an answer could be "RTFM", which I'd gladly do.

  • I found partial answers to my question at elinux.org which states that a user cannot modify ROM but leaves the question open if BroadCom can modify ROM post-manufacture. The wiki also states that since the ROM can't be reprogrammed by a user, there's no risk of bricking the device. "It is programmed into the SoC itself during manufacture of the RPi and cannot be reprogrammed by a user." "Because of this boot process, use of an SD card to boot the RPi is mandatory. This does however mean that you cannot 'brick' the device." – Statement Nov 15 '15 at 22:18
  • Third find; it appears that bootrom is readable, although I haven't tried accessing it myself yet. Herman H Hermitage has a public repository with examples. – Statement Nov 15 '15 at 22:20

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