CONFIG_UDBG_RTAS_CONSOLE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_UDBG_RTAS_CONSOLE.
Result is shown for kernelversion 6.9.9
RTAS based debug console
configname: CONFIG_UDBG_RTAS_CONSOLE
Linux Kernel Configuration
└─>Platform support
└─>RTAS based debug console