default or selected kernelversion does not have config value CONFIG_BKL.
Result is shown for kernelversion 5.4.69

Big Kernel Lock

configname: CONFIG_BKL

Linux Kernel Configuration
└─>Big Kernel Lock
In linux kernel since version 2.6.37 (release Date: 2011-01-04)  
This is the traditional lock that is used in old code instead
of proper locking. All drivers that use the BKL should depend
on this symbol.
Say Y here unless you are working on removing the BKL.