The mcelog command doesn't support AMD processors and the resulting error message, which appears once in the syslog at boot-up, causes confusion and anxiety. For a list of supported CPUs type
mcelog --help
and to test whether the current CPU is supported run
mcelog --is-cpu-supported
which returns no error message and a return code of zero if the CPU is on the supported list, or the error message and a non-zero return code in the case of an unsupported CPU