CONFIG_MACH_X1000 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_MACH_X1000 (not configurable)

configname: CONFIG_MACH_X1000

Linux Kernel Configuration
└─>MACH_X1000
In linux kernel since version 5.1 (release Date: 2019-05-05)