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

CONFIG_CPU_NOP_WORKAROUNDS (not configurable)

configname: CONFIG_CPU_NOP_WORKAROUNDS

Linux/MIPS Kernel Configuration
└─>CPU selection
└─>CPU_NOP_WORKAROUNDS
In linux kernel since version 2.6.34 (release Date: 2010-05-16)