CONFIG_HOTPLUG_CPU (not configurable)

modulename: hotplug.ko

and/or

hotplug-cpu.ko

and/or

cpu_hotplug.ko

configname: CONFIG_HOTPLUG_CPU

Linux Kernel Configuration
└─>Processor type and features
└─>HOTPLUG_CPU
In linux kernel since version 2.6.12  
depends
CONFIG_SMP