# Building the ng_sample module from /usr/src/sys/netgraph7 (guest):
# /root/ngsample/Makefile:
#   .PATH: /usr/src/sys/netgraph7
#   KMOD= ng_sample
#   SRCS= ng_sample.c
#   CFLAGS+= -I/usr/src/sys/netgraph7
#   .include <bsd.kmod.mk>
$ make
... cc -O2 ... -DKLD_MODULE ... -c /usr/src/sys/netgraph7/ng_sample.c
cc -Wl,--build-id=sha1 -nostdlib ... -r -o ng_sample.ko ng_sample.o
RC=0
-rw-r--r--  1 root  wheel  8480 Sep 14 19:06 ng_sample.ko

# ng7 base and socket modules likewise:
#   /root/ng7base (KMOD=netgraph, SRCS=ng_base.c ng_parse.c): BASE_RC=0
#   /root/ng7sock (KMOD=ng_socket, SRCS=ng_socket.c):         SOCK_RC=0
# All three kldload cleanly together (after the stock v1 netgraph modules
# were unloaded / the guest rebooted):
#   NG7_BASE_LOADED / NG7_SOCK_LOADED / NG_SAMPLE_LOADED
#
# Shipping status: ng_sample is NOT in the default build:
#   - absent from sys/netgraph7/Makefile SUBDIR (no ng_sample subdir entry;
#     the file sits directly in sys/netgraph7/ with no per-module Makefile)
#   - no "ng_sample" line in sys/conf/files (kernel config)
#   - /boot/kernel contains no ng_sample.ko (26 ng_*.ko modules, all v1)