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

CONFIG_NO_IOMEM (not configurable)

configname: CONFIG_NO_IOMEM

Linux Kernel Configuration
└─>UML-specific options
└─>NO_IOMEM
In linux kernel since version 2.6.21 (release Date: 2007-04-25)