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Arm Cortex-A55 Core Technical Reference Manual : On


In this mode, the core is on and fully operational.

The core can be initialized into the On mode. If the core does not use P-Channel, you can tie the core in the On mode by tying PREQ LOW.

When a transition to the On mode completes, all caches are accessible and coherent. Other than the normal architectural steps to enable caches, no additional software configuration is required.

When the core domain P-Channel is initialized into the On mode, either as a shortcut for entering that mode or as a tie-off for an unused P-Channel, it is an assumed transition from the Off mode. This includes an invalidation of any cache RAM within the core domain.