The sys.df file, defines the INCLUDES and DEFINES variables.
INCLUDES=" \
-Isys/include \
-Ibsd \
-Ibsd/sys \
-I${OS_DIR}/include/sys \
-Ibsd/machine \
-I${OS_DIR}/include/machine \
-I${OS_DIR}/include/chorus/iom \
-I${OS_DIR}/include/chorus \
-I${OS_DIR}/include/chorus/cx \
-I${NUCLEUS_DIR}/include/chorus \
-I${IOM_DIR}/include \
-I${OS_DIR}/include \
-I${NUCLEUS_DIR}/include \
-I${OS_DIR}/include/stdc \
-I${NUCLEUS_DIR}/include/stdc"
DEFINES="$DEFINES -DKERNEL -D_KERNEL -D__FreeBSD__ /
-DINET -DNO_CACHE -DMSDOSFS -DNFS -DIOM_MALLOC -DSHARED_FD"