Makefile

SOURCES = $(wildcard kernel/*.c drivers/*.c)
HEADERS = $(wildcard kernel/*.h drivers/*.h)
# Creates a list identical to sources but replaces ".c" with ".o"
OBJ = ${SOURCES:.c=.o}

# Cross compiler locations
GCC = /usr/bin/i686-elf-gcc
LD  = /usr/bin/i686-elf-ld
GDB = /usr/bin/gdb-multiarch

# -g: Use debugging symbols in gcc
CFLAGS = -g

QEMU = /usr/bin/qemu-system-i386

# First rule, catch all; ready final bootable image
os-image.bin: boot/boot.bin kernel.bin
	cat $^ > os-image.bin

# '--oformat binary' deletes all symbols as a collateral, so we don't need
# to 'strip' them manually on this case
kernel.bin: boot/kernel_entry.o ${OBJ}
	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary

# Used for debugging purposes
kernel.elf: boot/kernel_entry.o ${OBJ}
	${LD} -o $@ -Ttext 0x1000 $^ 

run: os-image.bin
	${QEMU} -fda os-image.bin

# Open the connection to qemu and load our kernel-object file with symbols
debug: os-image.bin kernel.elf
	${QEMU} -s -fda os-image.bin &
	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"

# Generic rules for wildcards
# To make an object, always compile from its .c
%.o: %.c ${HEADERS}
	${GCC} ${CFLAGS} -ffreestanding -c $< -o $@

%.o: %.asm
	nasm $< -f elf -o $@

%.bin: %.asm
	nasm $< -f bin -o $@

# Clean up all our build artifacts
clean:
	rm -rf *.bin *.dis *.o os-image.bin *.elf
	rm -rf kernel/*.o boot/*.bin drivers/*.o boot/*.o