Added qemu-gdb target

Makefile

@@ -116,7 +116,19 @@ qemu-remote:
 		-serial stdio \
 		-fda "$(BUILD)/disk.img"
 
-# -gdb tcp::26000 \
-# -S
-# -enable-kvm \
-# -cpu host \
+# Same as qemu, but with gdb options
+.PHONY: qemu-gdb
+qemu-gdb: $(BUILD)/disk.img
+	qemu-system-i386 \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 1 -m 2048 \
+		-machine q35 \
+		-net none \
+		-serial stdio \
+		-fda "$<" \
+		-gdb tcp::26000 \
+		-S
+
+# Do not use `-enable-kvm` or `-cpu host`,
+# this confuses gdb.