CONFIG_X86_MCE_NONFATAL is not available for thedefaultarchitecture x86.
Result is shown for architecture i386
default or selected kernelversion does not have config value CONFIG_X86_MCE_NONFATAL.
Result is shown for kernelversion 5.4.123

Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4

modulename:  non-fatal.ko

configname: CONFIG_X86_MCE_NONFATAL

Linux Kernel Configuration
└─>Processor type and features
└─>Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4
In linux kernel since version 2.6.12  
Enabling this feature starts a timer that triggers every 5 seconds which
will look at the machine check registers to see if anything happened.
Non-fatal problems automatically get corrected (but still logged).
Disable this if you don't want to see these messages.
Seeing the messages this option prints out may be indicative of dying hardware,
or out-of-spec (ie, overclocked) hardware.
This option only does something on certain CPUs.
(AMD Athlon/Duron and Intel Pentium 4)

source code:
depends
CONFIG_X86_MCE