Compatible ABI support

modulename: xfrm_compat.ko

configname: CONFIG_XFRM_USER_COMPAT

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Compatible ABI support
In linux kernel since version 5.1 (release Date: 2019-05-05)  
Transformation(XFRM) user configuration interface like IPsec
used by compatible Linux applications.

If unsure, say N.

source code:
net/xfrm/xfrm_compat.c