CONFIG_CPU_MICROMIPS is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
microMIPS
configname: CONFIG_CPU_MICROMIPS
SmartMIPS or microMIPS ASE support
└─>microMIPS
In linux kernel since version 3.1 (release Date: 2011-10-24)
When this option is enabled the kernel will be built using the
microMIPS ISA
microMIPS ISA