-/* OpenBIOS defined UART mappings, used before early_serial_setup */
-#define UART0_IO_BASE (u8 *) 0xE0000200
-#define UART1_IO_BASE (u8 *) 0xE0000300
+#if defined(__BOOTER__)
+/* OpenBIOS defined UART mappings, used by bootloader shim */
+#define UART0_IO_BASE 0xE0000200
+#define UART1_IO_BASE 0xE0000300
+#else
+/* head_44x.S created UART mapping, used before early_serial_setup.
+ * We cannot use default OpenBIOS UART mappings because they
+ * don't work for configurations with more than 512M RAM. --ebs
+ */
+#define UART0_IO_BASE 0xF0000200
+#define UART1_IO_BASE 0xF0000300
+#endif