This option allows you to change some of the ways that
Linux manages its memory internally. Most users will
only have one option here: FLATMEM. This is normal
and a correct option.

Some users of more advanced features like NUMA and
memory hotplug may have different options here.
DISCONTIGMEM is an more mature, better tested system,
but is incompatible with memory hotplug and may suffer
decreased performance over SPARSEMEM. If unsure between
"Sparse Memory" and "Discontiguous Memory", choose
"Discontiguous Memory".

If unsure, choose this option (Flat Memory) over any other.