CONFIG_HAVE_EFFICIENT_UNALIGNED_STRING_OPS is not available for thedefaultarchitecture x86.
Result is shown for architecture csky

Enable EFFICIENT_UNALIGNED_STRING_OPS for abiv2

configname: CONFIG_HAVE_EFFICIENT_UNALIGNED_STRING_OPS

Linux Kernel Configuration
└─>Processor type and features
└─>Enable EFFICIENT_UNALIGNED_STRING_OPS for abiv2
In linux kernel since version 5.2 (release Date: 2019-07-07)  
Say Y here to enable EFFICIENT_UNALIGNED_STRING_OPS. Some CPU models could
deal with unaligned access by hardware.