notlinuxkernel/Makefile at main · mitchellhalliday/notlinuxkernel · GitHub

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# ──────────────────────────────────────────────────────────────
#  notlinuxkernel — Makefile
# ──────────────────────────────────────────────────────────────
#
#  Build toolchain overview (all 32-bit, freestanding, no stdlib):
#
#   NASM          — assembles boot/boot.asm  → boot.o
#   GCC  (-m32)   — compiles  kernel/*.c     → *.o    (freestanding)
#   LD             — links all .o files using linker.ld → kernel binary
#   grub-mkrescue  — wraps the binary into a bootable ISO
#   QEMU           — boots the ISO in a virtual i386 PC
#
# ──────────────────────────────────────────────────────────────

# --- Tools ---------------------------------------------------------
ASM      = nasm
CC       = gcc
LD       = ld
GRUB     = grub-mkrescue
QEMU     = qemu-system-i386

# --- Flags ---------------------------------------------------------
ASMFLAGS = -f elf32

# -m32            : generate 32-bit code
# -ffreestanding  : no hosted environment (no libc)
# -fno-builtin    : don't use GCC builtins that assume libc
# -nostdlib       : don't link the standard library
# -Wall -Wextra   : all warnings
CFLAGS   = -m32 -std=gnu99 -ffreestanding -fno-builtin -nostdlib \
           -Wall -Wextra -O2 -g

LDFLAGS  = -m elf_i386 -T linker.ld

# --- Files ---------------------------------------------------------
ASM_SRC  = boot/boot.asm
C_SRC    = $(wildcard kernel/*.c)

ASM_OBJ  = $(patsubst boot/%.asm, build/%.o, $(ASM_SRC))
C_OBJ    = $(patsubst kernel/%.c, build/%.o, $(C_SRC))
OBJECTS  = $(ASM_OBJ) $(C_OBJ)

KERNEL   = build/notlinuxkernel.bin
ISO      = build/notlinuxkernel.iso

# --- Targets -------------------------------------------------------
.PHONY: all clean run iso test-host test-qemu

all: $(ISO)

# Assemble boot stub
build/%.o: boot/%.asm | build
	$(ASM) $(ASMFLAGS) $< -o $@

# Compile kernel C files
build/%.o: kernel/%.c | build
	$(CC) $(CFLAGS) -c $< -o $@

# Link everything into a flat binary (ELF)
$(KERNEL): $(OBJECTS)
	$(LD) $(LDFLAGS) -o $@ $^

# Build a bootable ISO with GRUB
$(ISO): $(KERNEL) grub/grub.cfg
	@mkdir -p build/isodir/boot/grub
	cp $(KERNEL) build/isodir/boot/notlinuxkernel.bin
	cp grub/grub.cfg build/isodir/boot/grub/grub.cfg
	$(GRUB) -o $@ build/isodir

# Boot in QEMU
run: $(ISO)
	$(QEMU) -cdrom $(ISO)

build:
	@mkdir -p build

clean:
	rm -rf build

# ──────────────────────────────────────────────────────────────
#  Host tests — compile natively, run on the host OS
# ──────────────────────────────────────────────────────────────
TEST_HOST_CFLAGS = -std=gnu99 -Wall -Wextra -O2 -g -DTEST_HOST -Ikernel -Itest
TEST_HOST_BIN    = build/test_host

test-host: $(TEST_HOST_BIN)
	@echo "=== Running host tests ==="
	@./$(TEST_HOST_BIN)

$(TEST_HOST_BIN): test/test_host_main.c test/test_kprintf.c test/test_string.c test/test_vga.c \
                  kernel/kernel.h kernel/kprintf.c kernel/kprintf.h kernel/string.c kernel/string.h \
                  test/test.h test/test_suites.h | build
	$(CC) $(TEST_HOST_CFLAGS) -fno-builtin -o $@ \
		test/test_host_main.c test/test_kprintf.c test/test_string.c test/test_vga.c kernel/kprintf.c kernel/string.c

# ──────────────────────────────────────────────────────────────
#  QEMU tests — compile into the kernel, boot in QEMU
# ──────────────────────────────────────────────────────────────
QEMU_TEST_CFLAGS  = $(CFLAGS) -DTEST_QEMU -Ikernel -Itest
QEMU_TEST_KERNEL  = build/test/notlinuxkernel-test.bin
QEMU_TEST_ISO     = build/test/notlinuxkernel-test.iso

QEMU_TEST_OBJECTS = build/boot.o \
					build/test/kernel.o build/test/serial.o build/test/string.o build/test/terminal.o build/test/kprintf.o \
					build/test/test_qemu_main.o build/test/test_kprintf.o build/test/test_string.o \
					build/test/test_vga.o

build/test/%.o: kernel/%.c | build/test
	$(CC) $(QEMU_TEST_CFLAGS) -c $< -o $@

build/test/%.o: test/%.c | build/test
	$(CC) $(QEMU_TEST_CFLAGS) -c $< -o $@

$(QEMU_TEST_KERNEL): $(QEMU_TEST_OBJECTS)
	$(LD) $(LDFLAGS) -o $@ $^

$(QEMU_TEST_ISO): $(QEMU_TEST_KERNEL) grub/grub.cfg
	@mkdir -p build/test/isodir/boot/grub
	cp $(QEMU_TEST_KERNEL) build/test/isodir/boot/notlinuxkernel.bin
	cp grub/grub.cfg build/test/isodir/boot/grub/grub.cfg
	$(GRUB) -o $@ build/test/isodir

test-qemu: $(QEMU_TEST_ISO)
	@echo "=== Running QEMU tests ==="
	@$(QEMU) -cdrom $(QEMU_TEST_ISO) -serial stdio -display none \
		-device isa-debug-exit,iobase=0xf4,iosize=0x04; \
		test $$? -eq 1

build/test:
	@mkdir -p build/test