toy_kernel/Makefile at bare_boot · eternalcomet/toy_kernel · GitHub

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# -----------Product Config-----------
# product name
PRODUCT_NAME = TOY_OS
BUILD_DIR ?= out
BUILD_BOOT_DIR = $(BUILD_DIR)/boot
# -----------Disk Image Config-----------
# image file name
DISK_IMAGE = $(BUILD_DIR)/disk.img
# disk size in MB, can be specified by command line
DISK_SIZE ?= 64
# sector size, 512 bytes by default
SECTOR_SIZE = 512
# partition offset in sector, 2048 by default because of 4KB alignment
PART_START = 2048
# end partition, partition size - 1 is the last partition
PART_END = $(shell echo $$((($(DISK_SIZE) * 1024 * 1024) / $(SECTOR_SIZE) - 1)))
# partition type, `0c` for FAT32
TYPE = 0c
# mount point
MOUNT_POINT ?= /mnt/toy_os
# -----------C Compiler Config-----------
CFLAGS = -Wall -static -fno-stack-protector -m32 -I.

.PHONY: clean mount unmount build_all run install

# -----------make-----------
run: install
	qemu-system-x86_64 -drive file=$(DISK_IMAGE),format=raw

install: build_all $(BUILD_BOOT_DIR)/flag_boot_installed

build_all: $(BUILD_DIR)/flag_inited $(BUILD_DIR)/boot/mbr_boot.bin

$(BUILD_DIR)/flag_inited:
	mkdir -p $(BUILD_DIR)
	mkdir -p $(BUILD_BOOT_DIR)
	touch $@

# make disk image
$(DISK_IMAGE):
	# create an empty disk image file filled with zeros
	dd if=/dev/zero of=$@ bs=1M count=$(DISK_SIZE)
	# create a MBR partition table with a FAT32 partition
	echo "o\nn\np\n1\n$(PART_START)\n$(PART_END)\nt\n$(TYPE)\nw\n" | fdisk $@
	# format the partition as FAT32
	mkfs.vfat -F 32 -n "$(PRODUCT_NAME)" --offset $(PART_START) $@


$(BUILD_BOOT_DIR)/mbr_boot_asm.o: boot/mbr_boot.asm
	mkdir -p $(BUILD_BOOT_DIR)
	nasm $< -f elf32 -o $(BUILD_BOOT_DIR)/mbr_boot_asm.o

$(BUILD_BOOT_DIR)/mbr_boot_c.o: boot/mbr_boot.c
	gcc $(CFLAGS) -nostdinc -fno-builtin -fno-pie -fno-pic -fno-strict-aliasing -O -s -c -o $(BUILD_BOOT_DIR)/mbr_boot_c.o $<

$(BUILD_BOOT_DIR)/mbr_boot.o: $(BUILD_BOOT_DIR)/mbr_boot_asm.o $(BUILD_BOOT_DIR)/mbr_boot_c.o
	# param explaination:
	# -N: Do not page align data, do not make text readonly
	# -e: Set entry point
	# -Ttext: Set address of .text section
	# -s: Strip all symbols
	ld -m elf_i386 -N -e boot_main -Ttext 0x7c00 -s $(BUILD_BOOT_DIR)/mbr_boot_asm.o $(BUILD_BOOT_DIR)/mbr_boot_c.o -o $(BUILD_BOOT_DIR)/mbr_boot.o

$(BUILD_BOOT_DIR)/mbr_boot.bin: $(BUILD_BOOT_DIR)/mbr_boot.o
	# param explaination:
	# -S: Strip all symbols and relocation information
	# -O: Output target
	# -j <name>: Only copy section <name> into the output
	objcopy -S -O binary -j .text -j .rodata $(BUILD_BOOT_DIR)/mbr_boot.o $(BUILD_BOOT_DIR)/mbr_boot.bin

$(BUILD_BOOT_DIR)/flag_boot_installed: $(BUILD_BOOT_DIR)/mbr_boot.bin $(DISK_IMAGE)
	# make sure the size is less than 440 bytes
	[ $(shell stat -c %s $(BUILD_BOOT_DIR)/mbr_boot.bin) -le 440 ]
	dd if=$< of=$(DISK_IMAGE) bs=440 count=1 conv=notrunc
	touch $@

# -----------clean-----------
clean:
	rm -rf $(BUILD_DIR)

# -----------mount disk image-----------
mount:
	sudo mkdir -p $(MOUNT_POINT)
	LOOPDEV=$$(sudo kpartx -av $(DISK_IMAGE) | head -n 1 | cut -d ' ' -f 3); \
	echo "Loop device: $$LOOPDEV"; \
	sudo mount /dev/mapper/$$LOOPDEV $(MOUNT_POINT)

# -----------unmount disk image-----------
unmount:
	sudo umount $(MOUNT_POINT)
	sudo kpartx -dv $(DISK_IMAGE)
	sudo rm -rf $(MOUNT_POINT)