Boot Process

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The WiiU has two processors -- an ARM core (inside the Latte, known as Starbuck) and a PowerPC core (Espresso). The boot process starts on the ARM core, which eventually bootstraps the PPC.

The code components involved in the WiiU's boot process are, in order:

  • (ARM) boot0 - A mask ROM which loads boot1 and verifies its SHA1 hash against that stored in OTP.
  • (ARM) boot1 - Lives in the first block of NAND and loads the IOSU from the NAND filesystem.
  • (ARM) IOSU - The IOSU is the operating system running on the ARM core. It bootstraps the PPC to start the Cafe OS.
  • (PPC) Cafe OS - The Cafe OS is the operating system running on the PowerPC core.