diff -BbuNr ioemu-remote-orig/hw/xen_platform.c ioemu-dir/hw/xen_platform.c
--- ioemu-remote-orig/hw/xen_platform.c	2008-07-10 11:55:14.803079583 +0100
+++ ioemu-dir/hw/xen_platform.c	2008-07-10 13:16:09.574483833 +0100
@@ -31,10 +30,64 @@
 
 extern FILE *logfile;
 
-static void platform_ioport_map(PCIDevice *pci_dev, int region_num,
-                                uint32_t addr, uint32_t size, int type)
+#define PFFLAG_ROM_LOCK 1 /* Sets whether ROM memory area is RW or RO */
+
+typedef struct PCIXenPlatformState
 {
-    /* nothing yet */
+  PCIDevice  pci_dev;
+  uint8_t    platform_flags;
+} PCIXenPlatformState;
+
+static uint32_t xen_platform_ioport_readb(void *opaque, uint32_t addr)
+{
+    PCIXenPlatformState *s = opaque;
+    int ret;
+
+    addr &= 0xff;
+
+    switch (addr)
+    {
+        case 0:
+            ret = s->platform_flags;
+            break;
+        default:
+            fprintf(logfile,"xen_platform: not implemented read(b) addr=0x%x\n", addr);
+            ret = 0;
+            break;
+    }
+    return ret;
+}
+                              
+static void xen_platform_ioport_writeb(void *opaque, uint32_t addr, uint32_t val)
+{
+    PCIXenPlatformState *d = opaque;
+
+    addr &= 0xff;
+    val  &= 0xff;
+
+    switch (addr)
+    {
+        case 0: /* Platform flags */
+        {
+            hvmmem_type_t mem_type = ( val & PFFLAG_ROM_LOCK ) ? HVMMEM_ram_ro : HVMMEM_ram_rw;
+            if ( xc_hvm_set_mem_type( xc_handle, domid, mem_type, 0xc0, 0x40) )
+                fprintf(logfile,"xen_platform: unable to change ro/rw state of ROM memory area! \n");
+            else
+                d->platform_flags = val & PFFLAG_ROM_LOCK;
+            break;
+        }
+        default:
+            fprintf(logfile,"xen_platform: not implemented write(b) addr=0x%x\n", addr);
+            break;
+    }
+}
+
+
+static void platform_ioport_map(PCIDevice *pci_dev, int region_num, uint32_t addr, uint32_t size, int type)
+{
+    PCIXenPlatformState *d = (PCIXenPlatformState *)pci_dev;
+    register_ioport_write(addr, size, 1, xen_platform_ioport_writeb, d);
+    register_ioport_read(addr, size, 1, xen_platform_ioport_readb, d);
 }
 
 static uint32_t platform_mmio_read(void *opaque, target_phys_addr_t addr)
@@ -112,30 +165,37 @@
 
 void xen_pci_save(QEMUFile *f, void *opaque)
 {
-    PCIDevice *d = opaque;
+    PCIXenPlatformState *d = opaque;
 
-    pci_device_save(d, f);
+    pci_device_save(&d->pci_dev, f);
+    qemu_put_8s(f, &d->platform_flags);
 }
 
 int xen_pci_load(QEMUFile *f, void *opaque, int version_id)
 {
-    PCIDevice *d = opaque;
+    PCIXenPlatformState *d = opaque;
 
     if (version_id != 1)
         return -EINVAL;
 
-    return pci_device_load(d, f);
+    pci_device_load(&d->pci_dev, f);
+    qemu_get_8s(f, &d->platform_flags);
+    /* Need to ensure the ROM r/w calls get made according to saved flag state. */
+    xen_platform_ioport_writeb(d,0,d->platform_flags);
+    return 0;
 }
 
 void pci_xen_platform_init(PCIBus *bus)
 {
-    PCIDevice *d;
+    PCIXenPlatformState *d;
     struct pci_config_header *pch;
 
+    d = qemu_mallocz(sizeof(PCIXenPlatformState));
+
     printf("Register xen platform.\n");
-    d = pci_register_device(bus, "xen-platform", sizeof(PCIDevice), -1, NULL,
-			    NULL);
-    pch = (struct pci_config_header *)d->config;
+    d = (PCIXenPlatformState *) pci_register_device(bus, "xen-platform",
+         sizeof(PCIXenPlatformState), -1, NULL, NULL);
+    pch = (struct pci_config_header *)d->pci_dev.config;
     pch->vendor_id = 0x5853;
     pch->device_id = 0x0001;
     pch->command = 3; /* IO and memory access */
@@ -151,13 +211,16 @@
     pch->subsystem_vendor_id = pch->vendor_id; /* Duplicate vendor id.  */
     pch->subsystem_id        = 0x0001;         /* Hardcode sub-id as 1. */
 
-    pci_register_io_region(d, 0, 0x100, PCI_ADDRESS_SPACE_IO,
+    pci_register_io_region((PCIDevice *)d, 0, 0x100, PCI_ADDRESS_SPACE_IO,
                            platform_ioport_map);
 
     /* reserve 16MB mmio address for share memory*/
-    pci_register_io_region(d, 1, 0x1000000, PCI_ADDRESS_SPACE_MEM_PREFETCH,
+    pci_register_io_region((PCIDevice *)d, 1, 0x1000000, PCI_ADDRESS_SPACE_MEM_PREFETCH,
 			   platform_mmio_map);
 
+    /* Make ROM areas read-write until set RO by guest or restore */
+    xen_platform_ioport_writeb(d,0,0);
+				   
     register_savevm("platform", 0, 1, xen_pci_save, xen_pci_load, d);
     printf("Done register platform.\n");
 }