I believe the idea here is that the coherency logic allows the A7 to be presented to the OS as simply another core that happens to run slower and consume less p

I believe the idea here is that the coherency logic allows the A7 to be presented to the OS as simply another core that happens to run slower and consume less power. This means that the OS is in control - the transition to low-power mode is handled by the OS scheduling processes on the little dogs while putting the big dogs into power saving states.