# Inspired by https://www.codemadness.org/openbsd-riscv64-vm.html
# mirror list: https://www.openbsd.org/ftp.html
mirror := https://ftp.lysator.liu.se/pub/OpenBSD/

# Version of OpenBSD to install
release := 7.5
release_short := $(shell echo ${release} | sed 's/\.//g')# Without dots (7.5 -> 75)

# Name of the disk image, named after the release
vmname := openBSD$(release_short)
diskname := $(vmname).qcow2

# Timestamp used for backup
UNIXTIME := $(shell date +%s)

# These are the packages that will be fetched from the OpenBSD mirror
opensbiname := opensbi-1.2.tgz
ubootname := u-boot-riscv64-2021.10p8.tgz

# PK used for release (not package, apparently) verification.
# Note that this is explicitly fetched from the OpenBSD mirror.
release_pubkey := openbsd-$(release_short)-base.pub
release_pubkey_url := https://ftp.openbsd.org/pub/OpenBSD/$(release)/$(release_pubkey)

# Specify how we want curl to behave
CURL := @curl --progress-bar -O

# The miniroot image is the installer image
minirootname := miniroot$(release_short).img

# QEMU arguments
QEMU_ARGS := -machine virt -nographic -m 2048M -smp 2 
QEMU_ARGS += -bios share/opensbi/generic/fw_jump.bin 
QEMU_ARGS += -kernel share/u-boot/qemu-riscv64_smode/u-boot.bin 
QEMU_ARGS += -netdev user,id=net0,ipv6=off -device virtio-net-device,netdev=net0
QEMU_ARGS += -drive file=$(diskname),format=qcow2,id=hd0 -device virtio-blk-device,drive=hd0

# Fetch the public key used to verify the release
$(release_pubkey):
	$(CURL) ${release_pubkey_url}

# Fetch the miniroot image and its checksums -> verify with signify
$(minirootname): $(release_pubkey)
	$(CURL) ${mirror}/${release}/riscv64/${minirootname}
	$(CURL) ${mirror}/${release}/riscv64/SHA256
	$(CURL) ${mirror}/${release}/riscv64/SHA256.sig
	signify -C -p ${release_pubkey} -x SHA256.sig $(minirootname)

# Allocate a qcow2 disk image, this is analogous to a hard drive
$(diskname):
	qemu-img create -f qcow2 ${diskname} 10G

# Fetches the amd64 repository keys and checksums
repokeys: $(release_pubkey)
	$(CURL) ${mirror}/${release}/packages/amd64/SHA256
	$(CURL) ${mirror}/${release}/packages/amd64/SHA256.sig

# Verify the checksums of the packages in the current directory
checksums: repokeys
	cksum -a sha256 --ignore-missing -c SHA256

# Fetch OpenSBI
$(opensbiname): repokeys
	$(CURL) ${mirror}/${release}/packages/amd64/${opensbiname}
	@# signify -C -p ${release_pubkey} -x SHA256.sig $(opensbiname)
	@tar -xzf ${opensbiname} share/opensbi/generic/fw_jump.bin

# Fetch U-Boot
$(ubootname): repokeys
	$(CURL) ${mirror}/${release}/packages/amd64/${ubootname}
	@# signify -C -p ${release_pubkey} -x SHA256.sig $(ubootname)
	@tar -xzf ${ubootname} share/u-boot/qemu-riscv64_smode/u-boot.bin

# Installer pulls all the pieces together and starts the VM with the installer attached as a drive (with correct boot order)
installer: $(minirootname) $(diskname) $(opensbiname) $(ubootname)
	make checksums
	@echo "Starting VM with installer..."
	@qemu-system-riscv64 -drive file=$(minirootname),format=raw,id=cd0 -device virtio-blk-device,drive=cd0 $(QEMU_ARGS)

# Run doesn't fetch anything, it just starts the VM with the disk (qcow2) image
run:
	@echo "Starting VM from disk image..."
	@qemu-system-riscv64 $(QEMU_ARGS)

# Creates a compressed archive of the disk image
backup:
	@echo "Backing up disk image..."
	qemu-img convert -c -O qcow2 $(diskname) $(vmname)_$(UNIXTIME).qcow2
	qemu-img info $(vmname)_$(UNIXTIME).qcow2
	tar -czvf $(vmname)_$(UNIXTIME).tar.gz $(vmname)_$(UNIXTIME).qcow2

# Clean up the directory
clean:
	rm -f ${minirootname} ${diskname} ${opensbiname} ${ubootname} ${release_pubkey} SHA256 SHA256.sig
	rm -rf share

# Clean, but also remove backups and disk images
superclean: clean
	rm -f $(vmname)_*.qcow2 $(vmname)_*.tar.gz

.PHONY: installer run clean backup