CONFIG_NR_CPUS_DEFAULT_64 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
CONFIG_NR_CPUS_DEFAULT_64 (not configurable)
configname: CONFIG_NR_CPUS_DEFAULT_64
Linux/MIPS Kernel Configuration
└─>Kernel type
└─>NR_CPUS_DEFAULT_64