CONFIG_AUXILIARY_BUS (not configurable)

modulename: auxiliary.ko

and/or

auxiliary_sysfs.ko

configname: CONFIG_AUXILIARY_BUS

Linux Kernel Configuration
└─>Device Drivers
└─>Generic Driver Options
└─>AUXILIARY_BUS
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
source code:
drivers/base//auxiliary.c