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

CONFIG_MIPS_AUTO_PFN_OFFSET (not configurable)

configname: CONFIG_MIPS_AUTO_PFN_OFFSET

Linux Kernel Configuration
└─>MIPS_AUTO_PFN_OFFSET
In linux kernel since version 4.2 (release Date: 2015-08-30)