What:		/sys/firmware/devicetree/overlays/
Date:		October 2015
Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Description:
		This directory contains the applied device tree overlays of
		the running system, as directories of the overlay id.

What:		/sys/firmware/devicetree/overlays/enable
Date:		October 2015
Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Description:
		The master enable switch, by default is 1, and when
		set to 0 it cannot be re-enabled for security reasons.

		The discussion about this switch takes place in:
		http://comments.gmane.org/gmane.linux.drivers.devicetree/101871

		Kees Cook:
		"Coming from the perspective of drawing a bright line between
		kernel and the root user (which tends to start with disabling
		kernel module loading), I would say that there at least needs
		to be a high-level one-way "off" switch for the interface so
		that systems that have this interface can choose to turn it off
		during initial boot, etc."

What:		/sys/firmware/devicetree/overlays/<id>
Date:		October 2015
Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Description:
		Each directory represents an applied overlay, containing
		the following attribute files.

What:		/sys/firmware/devicetree/overlays/<id>/can_remove
Date:		October 2015
Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Description:
		The attribute set to 1 means that the overlay can be removed,
		while 0 means that the overlay is being overlapped therefore
		removal is prohibited.

What:		/sys/firmware/devicetree/overlays/<id>/<fragment-name>/
Date:		October 2015
Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Description:
		Each of these directories contain information about of the
		particular overlay fragment.

What:		/sys/firmware/devicetree/overlays/<id>/<fragment-name>/target
Date:		October 2015
Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Description:
		The full-path of the target of the fragment