diff --git a/meta-yocto/conf/local.conf.sample b/meta-yocto/conf/local.conf.sample
index ca8636c..e33ffd9 100644
--- a/meta-yocto/conf/local.conf.sample
+++ b/meta-yocto/conf/local.conf.sample
@@ -222,3 +222,10 @@ PATCHRESOLVE = "noop"
 # track the version of this file when it was generated. This can safely be ignored if
 # this doesn't mean anything to you.
 CONF_VERSION = "1"
+
+# Incremental image generation(only for rpm based rootfs currently), the rootfs
+# would be totally removed and re-created in the second generation by default,
+# but with INC_IMAGE_GEN = "1", the rootfs would be kept, and will do
+# update(remove/add some pkgs) on it.
+# NOTE: This is not suggested when you want to create a productive rootfs
+#INC_IMAGE_GEN = "1"