# oob5662.ko build (guest /root/poc5662, kernel 6.5-DEVELOPMENT X86_64_GENERIC)
$ { echo KMOD=oob5662; echo SRCS=oob5662.c; echo SYSDIR=/usr/src/sys; echo '.include "/usr/src/sys/conf/kmod.mk"'; } > Makefile && make
cc  -O2 -pipe -D_KERNEL -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wcast-qual -Wold-style-definition -Wmissing-include-dirs -Wno-pointer-sign -Winit-self -Wundef -Wno-unused-but-set-variable -std=gnu11 -Werror -DKLD_MODULE -nostdinc [..] -c oob5662.c
cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv -r -Wl,-d -o oob5662.ko oob5662.o
(no warnings, no errors; -Werror clean) => oob5662.ko 7704 bytes