Bootstrapping sequence

From Linux4Nano Wiki

Please note that this is just a theory, and is by no means fact!

This especially is highly outdated knowledge, and pretty wrong in most places. --TheSeven 21:42, 23 September 2009 (UTC)

After reset/powerup both ARM core and DSP Calm loads from secure boot ROM specified by the S5L8700 information. The iPhone apparently uses a similar ROM at boot to either boot normally or load DFU mode. (Does the iPhone decrypt firmware at this stage also?) After that the apple bootloader(iBoot?) from utility flash is verified, loaded into RAM, probably decoded by DSP and executed. Here bootloader may change decryption routines and a key(or provide part of it). Also this is where Disk mode are probably stored and executed if required by the user. Diagnostic mode launches much later, when large part or all of OS already loaded. If those modes are not loaded, the bootloader execute the osos application layer. This is most likely where the Apple logo comes up.

Helpful pages

http://theiphonewiki.com/wiki/index.php?title=VROM_(S5L8900)

http://www.mobilehandsetdesignline.com/197800854

http://video.google.fr/videoplay?docid=713763707060529304&ei=ypFYSZ-5IpSw2QLn77XhDg&q=25c3