# DF-2929 module build (guest /root/df2929, final)
$ make
cc -O2 -pipe -I/usr/src/sys/dev/drm/include -D_KERNEL -Wall ... -Werror -DKLD_MODULE -nostdinc ... -c df2929_mod.c
cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv -r -Wl,-d -o df2929.ko df2929_mod.o
(no errors, no warnings; MODULE_DEPEND(df2929, drm, 1, 1, 1) pulls in /boot/kernel/drm.ko)

# fix build (guest /usr/src/sys/dev/drm/drm)
$ make obj && make
... linux_hrtimer.c compiled with fix ... -> drm.ko
(no errors; -Werror clean)