CONFIG_CPU_RM9000 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

RM9000

modulename: c-r4k.ko

and/or

dump_tlb.ko

and/or

r4k_fpu.ko

configname: CONFIG_CPU_RM9000

CPU type
└─>RM9000
In linux kernel since version 2.6.12  
source code:
arch/mips/mm/