CONFIG_HEXAGON is not available for thedefaultarchitecture x86.
Result is shown for architecture hexagon

CONFIG_HEXAGON (not configurable)

configname: CONFIG_HEXAGON

Linux Kernel Configuration
└─>HEXAGON
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Qualcomm Hexagon is a processor architecture designed for high
performance and low power across a wide variety of applications.

selects
CONFIG_HAVE_OPROFILE
CONFIG_USE_GENERIC_SMP_HELPERS
CONFIG_HAVE_IRQ_WORK
CONFIG_GENERIC_ATOMIC64
CONFIG_HAVE_PERF_EVENTS
CONFIG_HAVE_GENERIC_HARDIRQS
CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
CONFIG_GENERIC_HARDIRQS_NO_DEPRECATED
CONFIG_GENERIC_ALLOCATOR
CONFIG_GENERIC_IRQ_SHOW
CONFIG_HAVE_ARCH_KGDB
CONFIG_HAVE_ARCH_TRACEHOOK
CONFIG_NO_IOPORT
CONFIG_GENERIC_IOMAP