CONFIG_MACH_LOONGSON2EF is not available for the selected architecture x86.
Result is shown for architecture mips
Loongson-2E/F family of machines
configname: CONFIG_MACH_LOONGSON2EF
System type
└─>Loongson-2E/F family of machines
In linux kernel since version 5.1 (release Date: 2019-05-05)
This enables the support of early Loongson-2E/F family of machines.