CONFIG_IRQ_CPU_OCTEON is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_IRQ_CPU_OCTEON (not configurable)

configname: CONFIG_IRQ_CPU_OCTEON

Linux/MIPS Kernel Configuration
└─>IRQ_CPU_OCTEON
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
is depended by
CONFIG_CPU_CAVIUM_OCTEON