CONFIG_CAVIUM_OCTEON_REFERENCE_BOARD is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
default or selected kernelversion does not have config value CONFIG_CAVIUM_OCTEON_REFERENCE_BOARD.
Result is shown for kernelversion 6.2.5

Cavium Networks Octeon reference board

configname: CONFIG_CAVIUM_OCTEON_REFERENCE_BOARD

System type
└─>Cavium Networks Octeon reference board
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
This option supports all of the Octeon reference boards from Cavium
Networks. It builds a kernel that dynamically determines the Octeon
CPU type and supports all known board reference implementations.
Some of the supported boards are:
EBT3000
EBH3000
EBH3100
Thunder
Kodama
Hikari
Say Y here for most Octeon reference boards.