CONFIG_DEBUG_BFIN_HWTRACE_ON is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin

Turn on Blackfin's Hardware Trace

configname: CONFIG_DEBUG_BFIN_HWTRACE_ON

Linux Kernel Configuration
└─>Kernel hacking
└─>Turn on Blackfin's Hardware Trace
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
All Blackfins include a Trace Unit which stores a history of the last
16 changes in program flow taken by the program sequencer. The history
allows the user to recreate the program sequencer’s recent path. This
can be handy when an application dies - we print out the execution
path of how it got to the offending instruction.

By turning this off, you may save a tiny amount of power.