Add printf, gdb support, fix gdt
diff --git a/src/Makefile b/src/Makefile
index 7383c59..23ef8f4 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,4 +1,4 @@
-SOURCES = boot.o main.o descriptor_tables.o mem.o vga.o gdt_flush.o idt.o interrupts.o
+SOURCES = boot.o main.o descriptor_tables.o mem.o vga.o gdt_flush.o idt.o interrupts.o log.o
 CFLAGS = -nostdlib -nostdinc -fno-builtin -fno-stack-protector -ffreestanding -m32 -O2 -g
 LDFLAGS = -Tlink.ld -melf_i386
 ASMFLAGS = -felf
@@ -7,9 +7,18 @@
 	ld $(LDFLAGS) -o $@ $^
 
 clean:
-	rm -f *.o *.bin *.elf
+	rm -f *.o *.bin *.elf ../bin/*.iso
 
-qemu: install
+debug: kernel.elf
+	qemu-system-i386 -s -S -kernel kernel.elf &
+	@echo run "target remote localhost:1234" to connect to qemu
+	gdb
+	@pkill qemu-system-i38
+
+qemu: kernel.elf
+	qemu-system-i386 -monitor stdio -kernel kernel.elf
+
+qemu-iso: install
 	qemu-system-i386 -monitor stdio ../bin/bluejay.iso
 
 .s.o:
@@ -17,6 +26,7 @@
 
 install: kernel.elf
 	cp kernel.elf ../boot/
+	rm -f ../bin/bluejay.iso
 	grub-mkrescue -o ../bin/bluejay.iso ..
 
-.PHONY: install qemu clean
+.PHONY: install qemu clean qemu-iso debug