CONFIG_UML_DMA_EMULATION is not available for thedefaultarchitecture x86.
Result is shown for architecture um

CONFIG_UML_DMA_EMULATION (not configurable)

configname: CONFIG_UML_DMA_EMULATION

Linux Kernel Configuration
└─>UML-specific options
└─>UML_DMA_EMULATION
In linux kernel since version 5.2 (release Date: 2019-07-07)