Audio DSP Module

From The Apple Wiki

A "secret" coprocessor only in the S5L8900 devices. The phys / virt addresses are unknown.


I'll have to dig up my IDB to get the whole thing, but this is what I remember:

  • Register 0x0 - Calm2ADM Configuration Register
  • Register 0x50 - Calm2ADM Instruction Area (ie. pointer to payload)

IMG3 Obfuscation[edit]

This became known and looked into because in the 3.0 GM firmware release, for the S5L8900 devices, Apple made use of this to compute a "soft" GID Key to be used to decrypt the KBAG of the firmware image being loaded. The computation was based off of a hash of the first 0x1B000 of the running iBoot, so to get the correct output you needed to do some tricky patching.

See also[edit]