default or selected kernelversion does not have config value CONFIG_ARCH_HAS_FAST_MULTIPLIER.
Result is shown for kernelversion 6.9-rc5
CONFIG_ARCH_HAS_FAST_MULTIPLIER (not configurable)
configname: CONFIG_ARCH_HAS_FAST_MULTIPLIER
Linux Kernel Configuration
└─>Library routines
└─>ARCH_HAS_FAST_MULTIPLIER