(guest session — both KLD rigs)
$ sh /root/DF-5530/build_guest.sh
[usbpf_race.c]  cc -O2 -pipe -D_KERNEL -Wall ... -Werror -DKLD_MODULE -nostdinc -c usbpf_race.c
                cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv -r -Wl,-d -o df5530_race.ko usbpf_race.o
[bpfdetach_null.c] cc ... -c bpfdetach_null.c
                   cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv -r -Wl,-d -o bpfdetach_null.ko bpfdetach_null.o
-rw-r--r-- 1 root wheel 6072 Oct  7 00:13 df5530_race.ko
-rw-r--r-- 1 root wheel 3824 Oct  7 00:13 sink/bpfdetach_null.ko
BUILD_OK