diff -r 271ffb1c12eb tools/ioemu/hw/xen_platform.c
--- a/tools/ioemu/hw/xen_platform.c	Fri Jan 26 18:38:40 2007 +0000
+++ b/tools/ioemu/hw/xen_platform.c	Sat Jan 27 19:24:37 2007 +0800
@@ -31,19 +31,18 @@ extern FILE *logfile;
 
 static void platform_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 {
+#if defined(__i386__) || defined(__x86_64__)
+    mapcache_lock();
+    qemu_invalidate_map_cache();
+    mapcache_unlock();
+#endif
     return;
-}
-
-static uint32_t platform_ioport_read(void *opaque, uint32_t addr)
-{
-    return 0;
 }
 
 static void platform_ioport_map(PCIDevice *pci_dev, int region_num,
                                 uint32_t addr, uint32_t size, int type)
 {
-    register_ioport_write(addr, 16, 4, platform_ioport_write, NULL);
-    register_ioport_read(addr, 16, 1, platform_ioport_read, NULL);
+    register_ioport_write(addr, 1, 1, platform_ioport_write, NULL);
 }
 
 static uint32_t platform_mmio_read(void *opaque, target_phys_addr_t addr)
diff -r 271ffb1c12eb tools/ioemu/target-i386-dm/exec-dm.c
--- a/tools/ioemu/target-i386-dm/exec-dm.c	Fri Jan 26 18:38:40 2007 +0000
+++ b/tools/ioemu/target-i386-dm/exec-dm.c	Sat Jan 27 19:24:37 2007 +0800
@@ -129,18 +129,8 @@ int loglevel;
 int loglevel;
 
 
-#if defined(__i386__) || defined(__x86_64__)
-#define MAPCACHE
-#endif
-
 #ifdef MAPCACHE
-#include <pthread.h>
-static pthread_mutex_t mapcache_mutex;
-#define mapcache_lock() pthread_mutex_lock(&mapcache_mutex)
-#define mapcache_unlock() pthread_mutex_unlock(&mapcache_mutex)
-#else 
-#define mapcache_lock() ( (void)0 )
-#define mapcache_unlock() ( (void)0 )
+pthread_mutex_t mapcache_mutex;
 #endif
 
 
diff -r 271ffb1c12eb tools/ioemu/vl.c
--- a/tools/ioemu/vl.c	Fri Jan 26 18:38:40 2007 +0000
+++ b/tools/ioemu/vl.c	Sat Jan 27 19:24:37 2007 +0800
@@ -285,7 +285,7 @@ int register_ioport_write(int start, int
     for(i = start; i < start + length; i += size) {
         ioport_write_table[bsize][i] = func;
         if (ioport_opaque[i] != NULL && ioport_opaque[i] != opaque)
-            hw_error("register_ioport_read: invalid opaque");
+            hw_error("register_ioport_write: invalid opaque");
         ioport_opaque[i] = opaque;
     }
     return 0;
@@ -5826,6 +5826,10 @@ static struct map_cache *mapcache_entry;
 static struct map_cache *mapcache_entry;
 static unsigned long nr_buckets;
 
+/* For most cases (>99.9%), the page address is the same. */
+static unsigned long last_address_index = ~0UL;
+static uint8_t      *last_address_vaddr;
+
 static int qemu_map_cache_init(unsigned long nr_pages)
 {
     unsigned long max_pages = MAX_MCACHE_SIZE >> PAGE_SHIFT;
@@ -5862,10 +5866,6 @@ uint8_t *qemu_map_cache(target_phys_addr
     unsigned long address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
     unsigned long address_offset = phys_addr & (MCACHE_BUCKET_SIZE-1);
 
-    /* For most cases (>99.9%), the page address is the same. */
-    static unsigned long last_address_index = ~0UL;
-    static uint8_t      *last_address_vaddr;
-
     if (address_index == last_address_index)
         return last_address_vaddr + address_offset;
 
@@ -5904,6 +5904,30 @@ uint8_t *qemu_map_cache(target_phys_addr
     last_address_vaddr = entry->vaddr_base;
 
     return last_address_vaddr + address_offset;
+}
+
+void qemu_invalidate_map_cache(void)
+{
+    unsigned long i;
+
+    for (i = 0; i < nr_buckets; i++) {
+        struct map_cache *entry = &mapcache_entry[i];
+
+        if (entry->vaddr_base == NULL)
+            continue;
+
+        errno = munmap(entry->vaddr_base, MCACHE_BUCKET_SIZE);
+        if (errno) {
+            fprintf(logfile, "unmap fails %d\n", errno);
+            exit(-1);
+        }
+
+        entry->paddr_index = 0;
+        entry->vaddr_base  = NULL;
+    }
+
+    last_address_index =  ~0UL;
+    last_address_vaddr = NULL;
 }
 #endif
 
diff -r 271ffb1c12eb tools/ioemu/vl.h
--- a/tools/ioemu/vl.h	Fri Jan 26 18:38:40 2007 +0000
+++ b/tools/ioemu/vl.h	Sat Jan 27 19:24:37 2007 +0800
@@ -158,6 +158,7 @@ extern FILE *logfile;
 
 
 #if defined(__i386__) || defined(__x86_64__)
+#define MAPCACHE
 #if defined(__i386__) 
 #define MAX_MCACHE_SIZE    0x40000000 /* 1GB max for x86 */
 #define MCACHE_BUCKET_SHIFT 16
@@ -174,6 +175,17 @@ struct map_cache {
 };
 
 uint8_t *qemu_map_cache(target_phys_addr_t phys_addr);
+void     qemu_invalidate_map_cache(void);
+#endif
+
+#ifdef MAPCACHE
+#include <pthread.h>
+extern  pthread_mutex_t mapcache_mutex;
+#define mapcache_lock() pthread_mutex_lock(&mapcache_mutex)
+#define mapcache_unlock() pthread_mutex_unlock(&mapcache_mutex)
+#else 
+#define mapcache_lock()   ((void)0)
+#define mapcache_unlock() ((void)0)
 #endif
 
 extern int xc_handle;
diff -r 271ffb1c12eb unmodified_drivers/linux-2.6/platform-pci/platform-pci.c
--- a/unmodified_drivers/linux-2.6/platform-pci/platform-pci.c	Fri Jan 26 18:38:40 2007 +0000
+++ b/unmodified_drivers/linux-2.6/platform-pci/platform-pci.c	Sat Jan 27 19:24:52 2007 +0800
@@ -214,6 +214,18 @@ static uint64_t get_callback_via(struct 
 #endif
 }
 
+#if defined(__i386__) || defined(__x86_64__)
+/* the port for invalidating Qemu mapcache */
+static uint16_t qemu_invl_mapcache_port;
+
+/* tell Qemu to invalidate its mapcache */
+void qemu_invalidate_map_cache(void)
+{
+    outb(0, qemu_invl_mapcache_port);
+}
+EXPORT_SYMBOL(qemu_invalidate_map_cache);
+#endif
+
 static int __devinit platform_pci_init(struct pci_dev *pdev,
 				       const struct pci_device_id *ent)
 {
@@ -238,6 +250,10 @@ static int __devinit platform_pci_init(s
 		printk(KERN_WARNING DRV_NAME ":no resources found\n");
 		return -ENOENT;
 	}
+
+#if defined(__i386__) || defined(__x86_64__)
+    qemu_invl_mapcache_port = ioaddr;
+#endif
 
 	if (request_mem_region(mmio_addr, mmio_len, DRV_NAME) == NULL)
 	{