CONFIG_DEBUG_LPC18XX_UART0 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
Kernel low-level debugging via LPC18xx/43xx UART0
configname: CONFIG_DEBUG_LPC18XX_UART0
Kernel low-level debugging port
└─>Kernel low-level debugging via LPC18xx/43xx 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 NXP LPC18xx/43xx UART0.
on NXP LPC18xx/43xx UART0.