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

Size of Trace buffer (in power of 2k)


Linux Kernel Configuration
└─>Kernel hacking
└─>Size of Trace buffer (in power of 2k)
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
This sets the size of the software buffer that the trace information
is kept in.
0 for (2^0) 1k, or 256 entries,
1 for (2^1) 2k, or 512 entries,
2 for (2^2) 4k, or 1024 entries,
3 for (2^3) 8k, or 2048 entries,
4 for (2^4) 16k, or 4096 entries