[meta-xilinx] Kernel module recipe

[Edward Wingate]

I'm trying to make a recipe to create a custom version of
rpmsg_freertos_statistic module that I'll use instead.  I used the
recipe template for incorporating Out-of-Tree Modules:
poky/meta-skeleton/recipes-kernel/hello-mod/hello-mod_0.1.bb

I copied ../kernel-source/drivers/rpmsg/rpmsg_freertos_statistic.c to
hello.c. Everything builds and I get hello.ko in
/lib/modules/4.0.0-xilinx-dev/extra in the root file system.

But when I use this module, I get these errors:

hello: no symbol version for register_rpmsg_driver
hello: Unknown symbol register_rpmsg_driver (err -22)
hello: no symbol version for rpmsg_destroy_ept
hello: Unknown symbol rpmsg_destroy_ept (err -22)
hello: no symbol version for unregister_rpmsg_driver
hello: Unknown symbol unregister_rpmsg_driver (err -22)
hello: no symbol version for rpmsg_create_ept
hello: Unknown symbol rpmsg_create_ept (err -22)
hello: no symbol version for rpmsg_send_offchannel_raw
hello: Unknown symbol rpmsg_send_offchannel_raw (err -22)
modprobe: can't load module hello (extra/hello.ko): Invalid argument

Can anyone tell me what I'm doing wrong?  Should I not be using the
out-of-kernel template recipe to do this?  Thanks for any help.