diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..778f9e8
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "chisel/difftest"]
+	path = chisel/difftest
+	url = https://github.com/OpenXiangShan/difftest.git
diff --git a/chisel/difftest b/chisel/difftest
new file mode 160000
index 0000000..ea4771b
--- /dev/null
+++ b/chisel/difftest
@@ -0,0 +1 @@
+Subproject commit ea4771bb7b8b8b908251011e861b85ef19c64089