CONFIG_DEBUG_MSM8974_UART is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Kernel low-level debugging messages via MSM 8974 UART

configname: CONFIG_DEBUG_MSM8974_UART

Kernel low-level debugging port
└─>Kernel low-level debugging messages via MSM 8974 UART
In linux kernel since version 3.13 (release Date: 2014-01-19)  
Say Y here if you want the debug print routines to direct
their output to the serial port on MSM 8974 devices.


depends
CONFIG_ARCH_MSM8974