default or selected kernelversion does not have config value CONFIG_K8_NB.
Result is shown for kernelversion 5.4.229

CONFIG_K8_NB (not configurable)

modulename: k8.ko

configname: CONFIG_K8_NB

Linux Kernel Configuration for x86
└─>Bus options (PCI etc.)
└─>K8_NB
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  
source code: