CONFIG_ARCH_NS9XXX is not available for the default architecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_NS9XXX.
Result is shown for kernelversion 5.6.17

NetSilicon NS9xxx

configname: CONFIG_ARCH_NS9XXX

ARM system type
└─> NetSilicon NS9xxx

Say Y here if you intend to run this kernel on a NetSilicon NS9xxx