CONFIG_SGI_SN_M_MODE is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

IP27 M-Mode

configname: CONFIG_SGI_SN_M_MODE

Node addressing mode
└─>IP27 M-Mode
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  
The nodes of Origin, Onyx, Fuel and Tezro systems can be configured
in either N-Modes which allows for more nodes or M-Mode which allows
for more memory. Your hardware is almost certainly running in
M-Mode, so choose M-mode here.