CONFIG_CPU_MIPSR1 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_CPU_MIPSR1 (not configurable)

configname: CONFIG_CPU_MIPSR1

Linux/MIPS Kernel Configuration
└─>CPU_MIPSR1
In linux kernel since version 2.6.15 (release Date: 2006-01-02)