diff --git a/meta-ast2400/conf/machine/include/ast2400.inc b/meta-ast2400/conf/machine/include/ast2400.inc
index 6e02283..54a2ad6 100644
--- a/meta-ast2400/conf/machine/include/ast2400.inc
+++ b/meta-ast2400/conf/machine/include/ast2400.inc
@@ -12,4 +12,6 @@
 
 MACHINE_EXTRA_RDEPENDS += "udev-aspeed-vuart"
 
+SERIAL_CONSOLES = "115200;ttyS4"
+
 require conf/machine/include/tune-arm926ejs.inc
diff --git a/meta-ast2500/conf/machine/include/ast2500.inc b/meta-ast2500/conf/machine/include/ast2500.inc
index 6d2feb6..c8fc6da 100644
--- a/meta-ast2500/conf/machine/include/ast2500.inc
+++ b/meta-ast2500/conf/machine/include/ast2500.inc
@@ -14,4 +14,7 @@
 MACHINE_EXTRA_RDEPENDS += "udev-aspeed-vuart"
 
 DEFAULTTUNE = "armv6-novfp"
+
+SERIAL_CONSOLES = "115200;ttyS4"
+
 require conf/machine/include/arm/arch-armv6.inc