CONFIG_CPU_SUBTYPE_SH7721 is not available for the selected architecture x86.
Result is shown for architecture sh
Support SH7721 processor
modulename: setup-sh7720.ko
configname: CONFIG_CPU_SUBTYPE_SH7721
Processor sub-type selection
└─>Support SH7721 processor
In linux kernel since version 2.6.25 (release Date: 2008-04-16)
Select SH7721 if you have a SH3-DSP SH7721 CPU.