CONFIG_DEBUG_ALPINE_UART0 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Kernel low-level debugging messages via Alpine UART0

configname: CONFIG_DEBUG_ALPINE_UART0

Kernel low-level debugging port
└─>Kernel low-level debugging messages via Alpine UART0
In linux kernel since version 4.1 (release Date: 2015-06-21)  
Say Y here if you want kernel low-level debugging support
on Alpine based platforms.