CONFIG_DEBUG_MVEBU_UART0_ALTERNATE is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
Kernel low-level debugging messages via MVEBU UART0 (new bootloaders)
configname: CONFIG_DEBUG_MVEBU_UART0_ALTERNATE
Kernel low-level debugging port
└─>Kernel low-level debugging messages via MVEBU UART0 (new bootloaders)
In linux kernel since version 4 (release Date: 2015-04-12)
Say Y here if you want kernel low-level debugging support
on MVEBU based platforms on UART0. (Armada XP, Armada 3xx,
Kirkwood, Dove, MV78xx0, Orion5x).
This option should be used with the new bootloaders
that remap the internal registers at 0xf1000000.
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.
on MVEBU based platforms on UART0. (Armada XP, Armada 3xx,
Kirkwood, Dove, MV78xx0, Orion5x).
This option should be used with the new bootloaders
that remap the internal registers at 0xf1000000.
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.