CONFIG_DMA_UNCACHED_256K is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_DMA_UNCACHED_256K.
Result is shown for kernelversion 6.7-rc3
Enable 256K DMA region
configname: CONFIG_DMA_UNCACHED_256K
Uncached DMA region
└─>Enable 256K DMA region