CONFIG_UDBG_RTAS_CONSOLE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
CONFIG_UDBG_RTAS_CONSOLE (not configurable)
configname: CONFIG_UDBG_RTAS_CONSOLE
Linux/PowerPC Kernel Configuration
└─>Platform support
└─>UDBG_RTAS_CONSOLE