From: Marc Zyngier [mailto:marc.zyngier@arm.com] 
Sent: Tuesday, September 8, 2015 6:28 PM

In my view, this makes the change a lot more palatable, and it can fit in exactly two patches:

1) add the acpi_subtable_proc stuff with the compatibility helpers
2) change arch/x86/kernel/acpi/boot.c to do whatever you want it
  to do

It will be a lot easier to review and to verify.

Thanks, Marc.
Sounds you're right, I'll try to follow KISS rule better next time. Will send updated patches.

Cheers,
Lukasz