CONFIG_RPMSG (not configurable)

modulename: virtio_rpmsg_bus.ko

configname: CONFIG_RPMSG

Linux Kernel Configuration
└─>Device Drivers
└─>Rpmsg drivers
└─>RPMSG
In linux kernel since version 3.1 (release Date: 2011-10-24)  
source code:
drivers/rpmsg/virtio_rpmsg_bus.c

is selected by
CONFIG_QCOM_APR