CONFIG_BF561_COREB is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_BF561_COREB.
Result is shown for kernelversion 6.7-rc3

Enable Core B loader

modulename: coreb.ko

configname: CONFIG_BF561_COREB

Linux Kernel Configuration
└─>BF561 Specific Configuration
└─>Enable Core B loader
In linux kernel since version 2.6.22 (release Date: 2007-07-08)  
source code:
arch/blackfin/mach-bf561/coreb.c
depends
CONFIG_BF561
NOT CONFIG_SMP