CONFIG_ARCH_RPC is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

RiscPC

configname: CONFIG_ARCH_RPC

Linux Kernel Configuration
└─>RiscPC
In linux kernel since version 2.6.12  
On the Acorn Risc-PC, Linux can support the internal IDE disk and
CD-ROM interface, serial and parallel port, and the floppy drive.


depends
CONFIG_ARCH_MULTI_V4
CONFIG_ATAGS
CONFIG_CPU_LITTLE_ENDIAN
CONFIG_GCC_VERSIONCONFIG_60000
CONFIG_GCC_VERSIONCONFIG_90100
CONFIG_MMU
NOT CONFIG_ARCH_FOOTBRIDGE
NOT CONFIG_ARCH_GEMINI
NOT CONFIG_ARCH_MOXART
NOT CONFIG_ARCH_MULTI_V4T
NOT CONFIG_ARCH_MULTI_V5
NOT CONFIG_ARCH_SA1100
NOT CONFIG_CC_IS_CLANG