A core like the M7 would be invisible to the OS entirely.
The M7 core is likely involved in the bootup process. Modern CPUs are so complicated that you need another microprocessor for assistance to boot the darn thing.
Things like DDR4 initialization, PCIe initialization, SATA initialization (woops, this computer doesn't have any SATA drives, time to turn the attached M.2 drive into a SATA drive... wait, no M.2 drive either. I guess the motherboard wants to boot through PXE, which requires the network controller to be initialized). Etc. etc.
Even something like reading from NAND Flash requires a complicated initialization dance, where a microcontroller would be useful.
I admit I'm mostly ignorant on the bootup process of modern chips: but I understand that they're very complicated beasts now.
Spot on. Even the power supplies providing all the different power domains have to be booted up in a precise sequence. Companies like Marvell usually sell a suite of power management chips just to deal with that - and extract more money out of customers cause no one can be bothered to stray too far from the reference design.
The M7 core is likely involved in the bootup process. Modern CPUs are so complicated that you need another microprocessor for assistance to boot the darn thing.
Things like DDR4 initialization, PCIe initialization, SATA initialization (woops, this computer doesn't have any SATA drives, time to turn the attached M.2 drive into a SATA drive... wait, no M.2 drive either. I guess the motherboard wants to boot through PXE, which requires the network controller to be initialized). Etc. etc.
Even something like reading from NAND Flash requires a complicated initialization dance, where a microcontroller would be useful.
I admit I'm mostly ignorant on the bootup process of modern chips: but I understand that they're very complicated beasts now.