CONFIG_SH_WRITETHROUGH is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Use write-through caching

configname: CONFIG_SH_WRITETHROUGH

Linux/SuperH Kernel Configuration
└─>System type
└─>Use write-through caching
In linux kernel since version 2.6.12  
Selecting this option will configure the caches in write-through
mode, as opposed to the default write-back configuration.

Since there's sill some aliasing issues on SH-4, this option will
unfortunately still require the majority of flushing functions to
be implemented to deal with aliasing.

If unsure, say N.