CONFIG_SYS_SUPPORTS_SCHED_SMT is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_SYS_SUPPORTS_SCHED_SMT (not configurable)

configname: CONFIG_SYS_SUPPORTS_SCHED_SMT

Linux/MIPS Kernel Configuration
└─>Kernel type
└─>SYS_SUPPORTS_SCHED_SMT
In linux kernel since version 2.6.25 (release Date: 2008-04-16)