CONFIG_CPU_HAS_LDSTEX is not available for thedefaultarchitecture x86.
Result is shown for architecture csky
CONFIG_CPU_HAS_LDSTEX (not configurable)
configname: CONFIG_CPU_HAS_LDSTEX
Linux Kernel Configuration
└─>CPU_HAS_LDSTEX
In linux kernel since version 4.2 (release Date: 2015-08-30)
For SMP, CPU needs "ldex&stex" instructions for atomic operations.