CONFIG_OUTER_CACHE is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_OUTER_CACHE (not configurable)

modulename: l2c-common.ko

configname: CONFIG_OUTER_CACHE

Linux Kernel Configuration
└─>OUTER_CACHE
In linux kernel since version 2.6.21 (release Date: 2007-04-25)  
source code:
arch/arm/mm/l2c-common.c