diff --git a/board/dbau1x00/dbau1x00.c b/board/dbau1x00/dbau1x00.c
index d29e8d591e..a13eeeb123 100644
--- a/board/dbau1x00/dbau1x00.c
+++ b/board/dbau1x00/dbau1x00.c
@@ -25,6 +25,7 @@
 #include <command.h>
 #include <asm/au1x00.h>
 #include <asm/mipsregs.h>
+#include <asm/io.h>
 
 long int initdram(int board_type)
 {
@@ -77,6 +78,9 @@ int checkboard (void)
 	default:
 		printf ("Unsupported cpu %d, proc_id=0x%x\n", proc_id >> 24, proc_id);
 	}
+
+	set_io_port_base(0);
+
 #ifdef CONFIG_IDE_PCMCIA
 	/* Enable 3.3 V on slot 0 ( VCC )
 	   No 5V */
diff --git a/board/gth2/gth2.c b/board/gth2/gth2.c
index ffeaf587b5..1593f02109 100644
--- a/board/gth2/gth2.c
+++ b/board/gth2/gth2.c
@@ -26,14 +26,13 @@
 #include <asm/au1x00.h>
 #include <asm/addrspace.h>
 #include <asm/mipsregs.h>
+#include <asm/io.h>
 #include <watchdog.h>
 
 #include "ee_access.h"
 
 static int wdi_status = 0;
 
-unsigned long mips_io_port_base = 0;
-
 #define SDRAM_SIZE ((64*1024*1024)-(12*4096))
 
 
@@ -147,6 +146,9 @@ int checkboard (void)
 	default:
 		printf ("Unsupported cpu %d, proc_id=0x%x\n", proc_id >> 24, proc_id);
 	}
+
+	set_io_port_base(0);
+
 #ifdef CONFIG_IDE_PCMCIA
 	/* PCMCIA is on a 36 bit physical address.
 	   We need to map it into a 32 bit addresses */
diff --git a/board/incaip/incaip.c b/board/incaip/incaip.c
index b5d9e00492..dbf0ecc5af 100644
--- a/board/incaip/incaip.c
+++ b/board/incaip/incaip.c
@@ -25,7 +25,7 @@
 #include <command.h>
 #include <asm/addrspace.h>
 #include <asm/inca-ip.h>
-
+#include <asm/io.h>
 
 extern uint incaip_get_cpuclk(void);
 
@@ -85,7 +85,6 @@ long int initdram(int board_type)
 
 int checkboard (void)
 {
-
 	unsigned long chipid = *INCA_IP_WDT_CHIPID;
 	int part_num;
 
@@ -107,5 +106,7 @@ int checkboard (void)
 
 	printf("CPU Speed %d MHz\n", incaip_get_cpuclk()/1000000);
 
+	set_io_port_base(0);
+
 	return 0;
 }
diff --git a/board/pb1x00/pb1x00.c b/board/pb1x00/pb1x00.c
index 40ac2a4d7c..95b7d8246e 100644
--- a/board/pb1x00/pb1x00.c
+++ b/board/pb1x00/pb1x00.c
@@ -25,6 +25,7 @@
 #include <command.h>
 #include <asm/au1x00.h>
 #include <asm/mipsregs.h>
+#include <asm/io.h>
 
 long int initdram(int board_type)
 {
@@ -69,6 +70,9 @@ int checkboard (void)
 	default:
 		printf ("Unsupported cpu %d, proc_id=0x%x\n", proc_id >> 24, proc_id);
 	}
+
+	set_io_port_base(0);
+
 #if defined(CONFIG_IDE_PCMCIA) && 0
 	/* Enable 3.3 V on slot 0 ( VCC )
 	   No 5V */
diff --git a/board/purple/purple.c b/board/purple/purple.c
index 4c3e5b44b5..74718afb48 100644
--- a/board/purple/purple.c
+++ b/board/purple/purple.c
@@ -26,6 +26,7 @@
 #include <asm/inca-ip.h>
 #include <asm/regdef.h>
 #include <asm/mipsregs.h>
+#include <asm/io.h>
 #include <asm/addrspace.h>
 #include <asm/cacheops.h>
 
@@ -145,6 +146,8 @@ int checkboard (void)
 
 	printf("CPU Speed %d MHz\n", CPU_CLOCK_RATE/1000000);
 
+	set_io_port_base(0);
+
 	return 0;
 }
 
diff --git a/board/tb0229/tb0229.c b/board/tb0229/tb0229.c
index e7914bd15b..61c2e9bd36 100644
--- a/board/tb0229/tb0229.c
+++ b/board/tb0229/tb0229.c
@@ -13,10 +13,9 @@
 #include <command.h>
 #include <asm/addrspace.h>
 #include <asm/inca-ip.h>
+#include <asm/io.h>
 #include <pci.h>
 
-unsigned long mips_io_port_base = 0;
-
 #if defined(CONFIG_PCI)
 static struct pci_controller hose;
 
@@ -26,17 +25,17 @@ void pci_init_board (void)
 }
 #endif
 
-
 long int initdram(int board_type)
 {
 	return get_ram_size (CFG_SDRAM_BASE, 0x8000000);
 }
 
-
 int checkboard (void)
 {
 	printf("Board: TANBAC TB0229 ");
 	printf("(CPU Speed %d MHz)\n", (int)CPU_CLOCK_RATE/1000000);
 
+	set_io_port_base(0);
+
 	return 0;
 }
diff --git a/common/cmd_ide.c b/common/cmd_ide.c
index 27cecac4ee..2202009f5f 100644
--- a/common/cmd_ide.c
+++ b/common/cmd_ide.c
@@ -54,10 +54,6 @@
 
 #ifndef __PPC__
 #include <asm/io.h>
-#ifdef __MIPS__
-/* Macros depend on this variable */
-unsigned long mips_io_port_base = 0;
-#endif
 #endif
 
 #ifdef CONFIG_IDE_8xx_DIRECT
diff --git a/include/asm-mips/io.h b/include/asm-mips/io.h
index cd4d5dc9d9..1e060f7c31 100644
--- a/include/asm-mips/io.h
+++ b/include/asm-mips/io.h
@@ -71,7 +71,21 @@
  * instruction, so the lower 16 bits must be zero.  Should be true on
  * on any sane architecture; generic code does not use this assumption.
  */
-extern unsigned long mips_io_port_base;
+extern const unsigned long mips_io_port_base;
+
+/*
+ * Gcc will generate code to load the value of mips_io_port_base after each
+ * function call which may be fairly wasteful in some cases.  So we don't
+ * play quite by the book.  We tell gcc mips_io_port_base is a long variable
+ * which solves the code generation issue.  Now we need to violate the
+ * aliasing rules a little to make initialization possible and finally we
+ * will need the barrier() to fight side effects of the aliasing chat.
+ * This trickery will eventually collapse under gcc's optimizer.  Oh well.
+ */
+static inline void set_io_port_base(unsigned long base)
+{
+	* (unsigned long *) &mips_io_port_base = base;
+}
 
 /*
  * Thanks to James van Artsdalen for a better timing-fix than
diff --git a/lib_mips/board.c b/lib_mips/board.c
index 91ccec04df..c1a0acf469 100644
--- a/lib_mips/board.c
+++ b/lib_mips/board.c
@@ -62,6 +62,11 @@ static ulong mem_malloc_start;
 static ulong mem_malloc_end;
 static ulong mem_malloc_brk;
 
+/*
+ * mips_io_port_base is the begin of the address space to which x86 style
+ * I/O ports are mapped.
+ */
+unsigned long mips_io_port_base = -1;
 
 /*
  * The Malloc area is immediately below the monitor copy in DRAM