I found following chart on Raspberry Pi boot process: enter image description here

This is from https://docplayer.net/1716512-Embedded-linux-systems.html and if I understand correctly, it is for Raspberry Pi 1. Is it still relevant for Raspberry Pi 2 or something has changed?

EDIT: this chart is relatively old and I found that 'loader.bin' is no longer used.

  • 1
    Same procedure for all of them, that is how my Pi 4 boots by loading the specifically named files it finds that are hardwired into the firmware.
    – user130167
    Commented Mar 3, 2021 at 12:26

1 Answer 1


The definitive documentation can be found on the RPF site here with a caveat that BCM2837 and BCM2837B0 based boards follow these steps here

All but the Pi 4 has a part SD / Part USB boot mode. This is where the SD card only contains one partition (boot) and the bootcode.bin file. The program in here is capable of loading the rest of the O/S from USB device rather than SD Card as documented above.

This mode is handy in that support for different USB chipsets is limited in later Pi models (I had a stack of USB => SATA connectors that did not work) but I have yet to find one that does not boot via SD-card with just bootcode.bin on it.

I think this needed Stretch or above but TBH cannot remember (blush)

The Pi 3 series made it much more complex by introducing GPIO control and the 4 adds to that as well!

  • your second paragraph (ergarding pi2B v1.2) suggests you can't use "bootcode.bin mode" on a pi1B or original pi2B - I can assure you, you can - in fact, bootcode.bin mode (as you've called it) works on all my pi1, pi2 and I'm fairly sure it worked on my pi3 before I enabled boot from USB mode Commented Mar 3, 2021 at 22:50
  • @JaromandaX Sorry its the PI 4 that cannot use this - answer corrected. Thanks for the heads up.
    – user130616
    Commented Mar 3, 2021 at 23:04
  • Do you mean that this chart is correct for all RPI apart from the fact that it is possible to boot from a source other than the sd card?
    – IzZy
    Commented Mar 4, 2021 at 0:36
  • @IzZy - not worked through it step by step. The links are kept unto date by the RPF so I'm loath to say yes as it may change in the future and this answer becomes invalid. Putting links to other sites are not the best answer but RPF have been reasonably consistent in the documentation layout. GITHUB maybe a better reference long term?
    – user130616
    Commented Mar 4, 2021 at 15:39
  • It seems that your links are not answering my question. Chart on question is about booting from SD card, when your links provide information about searching for boot source.
    – IzZy
    Commented Mar 4, 2021 at 16:24

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