diff --git a/src/main/scala/rocketchip/Configs.scala b/src/main/scala/rocketchip/Configs.scala
index 4dda1ee3..61467754 100644
--- a/src/main/scala/rocketchip/Configs.scala
+++ b/src/main/scala/rocketchip/Configs.scala
@@ -195,3 +195,15 @@ class WithJtagDTM extends Config (
     case _ => throw new CDEMatchError
   }
 )
+
+class WithNoPeripheryArithAMO extends Config (
+  (pname, site, here) => pname match {
+    case PeripheryBusKey => PeripheryBusConfig(arithAMO = false, beatBytes = 4)
+  }
+)
+
+class With64BitPeriphery extends Config (
+  (pname, site, here) => pname match {
+    case PeripheryBusKey => PeripheryBusConfig(arithAMO = true, beatBytes = 8)
+  }
+)