I'm considering using the i.MX 7 processor for a new design. The overall architecture appears to be similar to the i.MX 6, at least from comparing the block diagrams.
What mechanisms exist for communication between the Cortex-M4 core and the Cortex-A7 core(s)? Does the stock Linux kernel provide any such mechanisms (which likely would assume a specific RTOS or firmware running on the M4), or is this custom firmware for both processors in Freescale's offerings? The processors appear to share pretty much everything, so I would imagine you could implement a shared memory buffer with an atomic semaphore, or something along those lines.
Ideally, I would like to have the M4 firmware "take over" some peripherals while the A7 processor is in a low-power mode (i.e. manage periodic communication transfers or some data analysis until something "interesting" happens that requires the A7 to do something). From the block diagrams and the i.MX 6 SoloX reference manual, it appears the hardware doesn't preclude this.