CONFIG_BF51x is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_BF51x.
Result is shown for kernelversion 6.7-rc3

CONFIG_BF51x (not configurable)

configname: CONFIG_BF51x

Linux Kernel Configuration
└─>BF51x
In linux kernel since version 2.6.29 (release Date: 2009-03-23)