CONFIG_64BIT_PHYS_ADDR is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
default or selected kernelversion does not have config value CONFIG_64BIT_PHYS_ADDR.
Result is shown for kernelversion 6.5.1

CONFIG_64BIT_PHYS_ADDR (not configurable)

configname: CONFIG_64BIT_PHYS_ADDR

Linux Kernel Configuration
└─>Kernel type
└─>64BIT_PHYS_ADDR
In linux kernel since version 2.6.12