CONFIG_COMPAT_32 (not configurable)

modulename: vdso-image-32.ko

configname: CONFIG_COMPAT_32

Linux Kernel Configuration
└─>Binary Emulations
└─>COMPAT_32
In linux kernel since version 3.10 (release Date: 2013-06-30)  
source code:
arch/x86/entry/vdso/
selects
CONFIG_HAVE_UID16
CONFIG_OLD_SIGSUSPEND3