What:		/sys/devices/system/xen_cpu/
Date:		May 2012
Contact:	Liu, Jinsong <jinsong.liu@intel.com>
Description:
		A collection of global/individual Xen physical cpu attributes

		Individual physical cpu attributes are contained in
		subdirectories named by the Xen's logical cpu number, e.g.:
		/sys/devices/system/xen_cpu/xen_cpu#/


What:		/sys/devices/system/xen_cpu/xen_cpu#/online
Date:		May 2012
Contact:	Liu, Jinsong <jinsong.liu@intel.com>
Description:
		Interface to online/offline Xen physical cpus

		When running under Xen platform, it provide user interface
		to online/offline physical cpus, except cpu0 due to several
		logic restrictions and assumptions.