resolved the "undefined reference" errors by fixing a critical object file naming collision in the build system.

Author: PythonPlumber

Makefile

@@ -3,9 +3,9 @@ AS := nasm
 LD := i686-linux-gnu-gcc
 OBJCOPY := i686-linux-gnu-objcopy
 
-CFLAGS := -ffreestanding -O2 -Wall -Wextra -m32 -fno-pie -fno-stack-protector -nostdlib -nostdinc -Iinclude -msse -msse2
+CFLAGS := -ffreestanding -O2 -Wall -Wextra -m32 -fno-pie -fno-PIC -fno-stack-protector -nostdlib -nostdinc -Iinclude -msse -msse2
 ASFLAGS := -f elf32
-LDFLAGS := -T linker.ld -nostdlib -m32 -Wl,-z,noexecstack
+LDFLAGS := -T linker.ld -nostdlib -m32 -no-pie -Wl,-z,noexecstack
 
 SRC_DIR := src
 BUILD_DIR := build
@@ -15,10 +15,10 @@ MODEL_OBJ := $(BUILD_DIR)/model.o
 ASM_SRCS := $(shell find $(SRC_DIR) -name "*.s")
 C_SRCS := $(filter-out $(SRC_DIR)/drivers/vga.c, $(shell find $(SRC_DIR) -name "*.c"))
 
-ASM_OBJS := $(patsubst $(SRC_DIR)/%.s,$(BUILD_DIR)/%.o,$(ASM_SRCS))
-C_OBJS := $(patsubst $(SRC_DIR)/%.c,$(BUILD_DIR)/%.o,$(C_SRCS))
+ASM_OBJS := $(patsubst $(SRC_DIR)/%.s,$(BUILD_DIR)/%.s.o,$(ASM_SRCS))
+C_OBJS := $(patsubst $(SRC_DIR)/%.c,$(BUILD_DIR)/%.c.o,$(C_SRCS))
 
-BOOT_OBJ := $(BUILD_DIR)/boot.o
+BOOT_OBJ := $(BUILD_DIR)/boot.s.o
 OTHER_OBJS := $(sort $(filter-out $(BOOT_OBJ),$(ASM_OBJS) $(C_OBJS)))
 OBJS := $(BOOT_OBJ) $(OTHER_OBJS)
 
@@ -31,11 +31,11 @@ all: $(BUILD_DIR) kernel.bin
 $(BUILD_DIR):
 	mkdir -p $(BUILD_DIR)
 
-$(BUILD_DIR)/%.o: $(SRC_DIR)/%.s
+$(BUILD_DIR)/%.s.o: $(SRC_DIR)/%.s
 	mkdir -p $(dir $@)
 	$(AS) $(ASFLAGS) $< -o $@
 
-$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c
+$(BUILD_DIR)/%.c.o: $(SRC_DIR)/%.c
 	mkdir -p $(dir $@)
 	$(CC) $(CFLAGS) -c $< -o $@