null :=
space := $(null) $(null)
KERNVER ?= $(lastword $(subst /,$(space),$(wildcard /lib/modules/*/)))

# slightly faster
MAKEFLAGS += -r

FORCE:

all: initramfs.img

initramfs.img: gen_init_cpio make modules.dep $(shell awk '$$1 == "file" { print $$3 }' cpio_list.txt)
	KERNVER=$(KERNVER) COMPRESSOR="zstd -19 -c -T0" ./make

gen_init_cpio: gen_init_cpio.c
	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $< -o $@

dropbear_ed25519_host_key:
	dropbearkey -t ed25519 -f $@

modules.dep.ver: FORCE
	if ! [ -f $@ ] || [ "$$(cat $@)" != "$(KERNVER)" ]; then echo $(KERNVER) > $@; fi

modules.dep: modules modules.dep.ver /lib/modules/$(KERNVER)/modules.dep
	awk '!/^#/ { print $$1 }' modules | xargs modinfo -F filename -k $(KERNVER) | sed -e 's:^/lib/modules/$(KERNVER)/:^:' | grep -f - /lib/modules/$(KERNVER)/modules.dep > $@

install: initramfs.img
	install -m644 initramfs.img /boot/initramfs.img.new
	if [ -e /boot/initramfs.img ]; then mv /boot/initramfs.img /boot/initramfs.img.old; fi
	mv /boot/initramfs.img.new /boot/initramfs.img

clean:
	rm -f initramfs.img initramfs.d gen_init_cpio modules.dep

-include initramfs.d

.PHONY: all install clean