CONFIG_FLATMEM (not configurable)

modulename: contig.ko

configname: CONFIG_FLATMEM

Linux Kernel Configuration
└─>Memory Management options
└─>FLATMEM
In linux kernel since version 2.6.13 (release Date: 2005-08-28)  
source code:
arch/ia64/mm/contig.c

is selected by
CONFIG_DYNAMIC_MEMSTART