15.1.4. Power down

In this state, the core is powered off. Software on the device must save all core state, so that it can be preserved over the power-down. Changing from power-down to running operation must include:

The defining characteristic of power down states is that they are destructive of context. This affects all the components that are switched off in a given state, including the core, and in deeper states other components of the system such as the GIC or platform-specific IP. Depending on how debug and trace power domains are organized, one or both of debug and trace context might be lost in some power-down states. Mechanisms must be provided to enable the operating system to perform the relevant context saving and restoring for each given state. Resumption of execution starts at the reset vector, and after this each OS must restore its context.

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