CONFIG_DEBUG_MVEBU_UART is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_DEBUG_MVEBU_UART.
Result is shown for kernelversion 6.5.1

Kernel low-level debugging messages via MVEBU UART (old bootloaders)


Kernel low-level debugging port
└─>Kernel low-level debugging messages via MVEBU UART (old bootloaders)
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Say Y here if you want kernel low-level debugging support
on MVEBU based platforms.

This option should be used with the old bootloaders
that left the internal registers mapped at
0xd0000000. As of today, this is the case on
platforms such as the Globalscale Mirabox or the
Plathome OpenBlocks AX3, when using the original

If the wrong DEBUG_MVEBU_UART* option is selected,
when u-boot hands over to the kernel, the system
silently crashes, with no serial output at all.