Discontiguous Memory

configname: CONFIG_DISCONTIGMEM_MANUAL

Memory model
└─>Discontiguous Memory
In linux kernel since version 2.6.13 (release Date: 2005-08-28)  
This option provides enhanced support for discontiguous
memory systems, over FLATMEM. These systems have holes
in their physical address spaces, and this option provides
more efficient handling of these holes.

Although "Discontiguous Memory" is still used by several
architectures, it is considered deprecated in favor of
"Sparse Memory".

If unsure, choose "Sparse Memory" over this option.