CONFIG_CPU_MIPS32_R6 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
MIPS32 Release 6 (EXPERIMENTAL)
configname: CONFIG_CPU_MIPS32_R6
CPU type
└─>MIPS32 Release 6 (EXPERIMENTAL)
In linux kernel since version 3.10 (release Date: 2013-06-30)
Choose this option to build a kernel for release 6 or later of the
MIPS32 architecture. New MIPS processors, starting with the Warrior
family, are based on a MIPS32r6 processor. If you own an older
processor, you probably need to select MIPS32r1 or MIPS32r2 instead.
MIPS32 architecture. New MIPS processors, starting with the Warrior
family, are based on a MIPS32r6 processor. If you own an older
processor, you probably need to select MIPS32r1 or MIPS32r2 instead.