CONFIG_ARCH_DISCONTIGMEM_ENABLE is not available for the selected architecture x86.
Result is shown for architecture ia64

CONFIG_ARCH_DISCONTIGMEM_ENABLE (not configurable)

configname: CONFIG_ARCH_DISCONTIGMEM_ENABLE

Linux Kernel Configuration
└─>Processor type and features
└─>ARCH_DISCONTIGMEM_ENABLE
In linux kernel since version 2.6.13 (release Date: 2005-08-28)
Say Y to support efficient handling of discontiguous physical memory,
for architectures which are either NUMA (Non-Uniform Memory Access)
or have huge holes in the physical address space for other reasons.
See <a href="https://www.kernel.org/doc/Documentation/vm/numa.rst">Documentation/vm/numa.rst</a> for more.