CONFIG_HUGETLB_PAGE_SIZE_512MB is not available for thedefaultarchitecture x86.
Result is shown for architecture sh
default or selected kernelversion does not have config value CONFIG_HUGETLB_PAGE_SIZE_512MB.
Result is shown for kernelversion 6.9.9

512MB

configname: CONFIG_HUGETLB_PAGE_SIZE_512MB

HugeTLB page size
└─>512MB
In linux kernel since version 2.6.12  
depends
CONFIG_CPU_SH5