Changes

==== Downgrade check ====

==== Downgrade check ====

The bootloader will check if someone attempted to downgrade it. A fuse array will be checked, if too many fuses are burnt the bootloader will panic. If too little are set, the bootloader will program the expected bitmap and force a reset. The fuse array and the expected number of burnt fuses is different on unit type 0 (non-retail) and unit type 1 (retail).

The bootloader verifies a lockdown fuse counter to prevent downgrading. A 32-bit lockdown value at fuse offset 0x1E4 is checked. If too many fuses are burned the bootloader will panic. If too few are burned, the bootloader will program the expected number of bits and force a reset. The expected lockdown value differs between unit type 0 (non-retail) and unit type 1 (retail).

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