diff --git a/.gitignore b/.gitignore
index 7a06b53..76cec07 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 !*/
+difftest/
 !/nemu/*
 !/nexus-am/*
 !/nanos-lite/*
@@ -13,3 +14,4 @@
 **/.cache
 **/result
 /.pre-commit-config.yaml
+**/.vscode/
diff --git a/.gitmodules b/.gitmodules
index 3d834b3..7553118 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,4 @@
 [submodule "am-kernels"]
 	path = am-kernels
 	url = https://git.xinyang.life/xin/am-kernels.git
+	branch = dev