CONFIG_SIBYTE_CFE is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
default or selected kernelversion does not have config value CONFIG_SIBYTE_CFE.
Result is shown for kernelversion 5.4.123

Booting from CFE

configname: CONFIG_SIBYTE_CFE

Linux/MIPS Kernel Configuration
└─>Machine selection
└─>Booting from CFE
In linux kernel since version 2.6.12  
Make use of the CFE API for enumerating available memory,
controlling secondary CPUs, and possibly console output.