]> git.proxmox.com Git - mirror_qemu.git/blobdiff - hw/qdev.c
qdev: fix hotplug when no -device is specified
[mirror_qemu.git] / hw / qdev.c
index 9519f5dd57a53184175804edfaf30fa53758f9bc..d0cf66de565f1d5860d1fcdb00db9bcd3098bad1 100644 (file)
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -36,6 +36,7 @@ static bool qdev_hot_removed = false;
 
 /* This is a nasty hack to allow passing a NULL bus to qdev_create.  */
 static BusState *main_system_bus;
+static void main_system_bus_create(void);
 
 DeviceInfo *device_info_list;
 
@@ -79,25 +80,43 @@ static DeviceInfo *qdev_find_info(BusInfo *bus_info, const char *name)
     return NULL;
 }
 
+static void qdev_property_add_legacy(DeviceState *dev, Property *prop,
+                                     Error **errp);
+
 static DeviceState *qdev_create_from_info(BusState *bus, DeviceInfo *info)
 {
     DeviceState *dev;
+    Property *prop;
 
     assert(bus->info == info->bus_info);
-    dev = qemu_mallocz(info->size);
+    dev = g_malloc0(info->size);
     dev->info = info;
     dev->parent_bus = bus;
     qdev_prop_set_defaults(dev, dev->info->props);
     qdev_prop_set_defaults(dev, dev->parent_bus->info->props);
     qdev_prop_set_globals(dev);
-    QLIST_INSERT_HEAD(&bus->children, dev, sibling);
+    QTAILQ_INSERT_HEAD(&bus->children, dev, sibling);
     if (qdev_hotplug) {
         assert(bus->allow_hotplug);
         dev->hotplugged = 1;
         qdev_hot_added = true;
     }
     dev->instance_id_alias = -1;
+    QTAILQ_INIT(&dev->properties);
     dev->state = DEV_STATE_CREATED;
+
+    for (prop = dev->info->props; prop && prop->name; prop++) {
+        qdev_property_add_legacy(dev, prop, NULL);
+        qdev_property_add_static(dev, prop, NULL);
+    }
+
+    for (prop = dev->info->bus_info->props; prop && prop->name; prop++) {
+        qdev_property_add_legacy(dev, prop, NULL);
+        qdev_property_add_static(dev, prop, NULL);
+    }
+
+    qdev_property_add_str(dev, "type", qdev_get_type, NULL, NULL);
+
     return dev;
 }
 
@@ -110,7 +129,12 @@ DeviceState *qdev_create(BusState *bus, const char *name)
 
     dev = qdev_try_create(bus, name);
     if (!dev) {
-        hw_error("Unknown device '%s' for bus '%s'\n", name, bus->info->name);
+        if (bus) {
+            hw_error("Unknown device '%s' for bus '%s'\n", name,
+                     bus->info->name);
+        } else {
+            hw_error("Unknown device '%s' for default sysbus\n", name);
+        }
     }
 
     return dev;
@@ -180,7 +204,7 @@ int qdev_device_help(QemuOpts *opts)
         return 1;
     }
 
-    if (!qemu_opt_get(opts, "?")) {
+    if (!driver || !qemu_opt_get(opts, "?")) {
         return 0;
     }
 
@@ -199,11 +223,45 @@ int qdev_device_help(QemuOpts *opts)
         if (!prop->info->parse) {
             continue;           /* no way to set it, don't show */
         }
-        error_printf("%s.%s=%s\n", info->name, prop->name, prop->info->name);
+        error_printf("%s.%s=%s\n", info->name, prop->name,
+                     prop->info->legacy_name ?: prop->info->name);
+    }
+    for (prop = info->bus_info->props; prop && prop->name; prop++) {
+        if (!prop->info->parse) {
+            continue;           /* no way to set it, don't show */
+        }
+        error_printf("%s.%s=%s\n", info->name, prop->name,
+                     prop->info->legacy_name ?: prop->info->name);
     }
     return 1;
 }
 
+static DeviceState *qdev_get_peripheral(void)
+{
+    static DeviceState *dev;
+
+    if (dev == NULL) {
+        dev = qdev_create(NULL, "container");
+        qdev_property_add_child(qdev_get_root(), "peripheral", dev, NULL);
+        qdev_init_nofail(dev);
+    }
+
+    return dev;
+}
+
+static DeviceState *qdev_get_peripheral_anon(void)
+{
+    static DeviceState *dev;
+
+    if (dev == NULL) {
+        dev = qdev_create(NULL, "container");
+        qdev_property_add_child(qdev_get_root(), "peripheral-anon", dev, NULL);
+        qdev_init_nofail(dev);
+    }
+
+    return dev;
+}
+
 DeviceState *qdev_device_add(QemuOpts *opts)
 {
     const char *driver, *path, *id;
@@ -255,7 +313,14 @@ DeviceState *qdev_device_add(QemuOpts *opts)
     id = qemu_opts_id(opts);
     if (id) {
         qdev->id = id;
-    }
+        qdev_property_add_child(qdev_get_peripheral(), qdev->id, qdev, NULL);
+    } else {
+        static int anon_count;
+        gchar *name = g_strdup_printf("device[%d]", anon_count++);
+        qdev_property_add_child(qdev_get_peripheral_anon(), name,
+                                qdev, NULL);
+        g_free(name);
+    }        
     if (qemu_opt_foreach(opts, set_property, qdev, 1) != 0) {
         qdev_free(qdev);
         return NULL;
@@ -289,6 +354,9 @@ int qdev_init(DeviceState *dev)
                                        dev->alias_required_for_version);
     }
     dev->state = DEV_STATE_INITIALIZED;
+    if (dev->hotplugged && dev->info->reset) {
+        dev->info->reset(dev);
+    }
     return 0;
 }
 
@@ -308,6 +376,11 @@ int qdev_unplug(DeviceState *dev)
     }
     assert(dev->info->unplug != NULL);
 
+    if (dev->ref != 0) {
+        qerror_report(QERR_DEVICE_IN_USE, dev->id?:"");
+        return -1;
+    }
+
     qdev_hot_removed = true;
 
     return dev->info->unplug(dev);
@@ -325,8 +398,7 @@ static int qdev_reset_one(DeviceState *dev, void *opaque)
 BusState *sysbus_get_default(void)
 {
     if (!main_system_bus) {
-        main_system_bus = qbus_create(&system_bus_info, NULL,
-                                      "main-system-bus");
+        main_system_bus_create();
     }
     return main_system_bus;
 }
@@ -371,17 +443,36 @@ void qdev_init_nofail(DeviceState *dev)
     DeviceInfo *info = dev->info;
 
     if (qdev_init(dev) < 0) {
-        error_report("Initialization of device %s failed\n", info->name);
+        error_report("Initialization of device %s failed", info->name);
         exit(1);
     }
 }
 
+static void qdev_property_del_all(DeviceState *dev)
+{
+    while (!QTAILQ_EMPTY(&dev->properties)) {
+        DeviceProperty *prop = QTAILQ_FIRST(&dev->properties);
+
+        QTAILQ_REMOVE(&dev->properties, prop, node);
+
+        if (prop->release) {
+            prop->release(dev, prop->name, prop->opaque);
+        }
+
+        g_free(prop->name);
+        g_free(prop->type);
+        g_free(prop);
+    }
+}
+
 /* Unlink device from bus and free the structure.  */
 void qdev_free(DeviceState *dev)
 {
     BusState *bus;
     Property *prop;
 
+    qdev_property_del_all(dev);
+
     if (dev->state == DEV_STATE_INITIALIZED) {
         while (dev->num_child_bus) {
             bus = QLIST_FIRST(&dev->child_bus);
@@ -394,13 +485,13 @@ void qdev_free(DeviceState *dev)
         if (dev->opts)
             qemu_opts_del(dev->opts);
     }
-    QLIST_REMOVE(dev, sibling);
+    QTAILQ_REMOVE(&dev->parent_bus->children, dev, sibling);
     for (prop = dev->info->props; prop && prop->name; prop++) {
         if (prop->info->free) {
             prop->info->free(dev, prop);
         }
     }
-    qemu_free(dev);
+    g_free(dev);
 }
 
 void qdev_machine_creation_done(void)
@@ -459,7 +550,7 @@ void qdev_connect_gpio_out(DeviceState * dev, int n, qemu_irq pin)
 
 void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd)
 {
-    qdev_prop_set_macaddr(dev, "mac", nd->macaddr);
+    qdev_prop_set_macaddr(dev, "mac", nd->macaddr.a);
     if (nd->vlan)
         qdev_prop_set_vlan(dev, "vlan", nd->vlan);
     if (nd->netdev)
@@ -468,6 +559,7 @@ void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd)
         qdev_prop_exists(dev, "vectors")) {
         qdev_prop_set_uint32(dev, "vectors", nd->nvectors);
     }
+    nd->instantiated = 1;
 }
 
 BusState *qdev_get_child_bus(DeviceState *dev, const char *name)
@@ -495,7 +587,7 @@ int qbus_walk_children(BusState *bus, qdev_walkerfn *devfn,
         }
     }
 
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         err = qdev_walk_children(dev, devfn, busfn, opaque);
         if (err < 0) {
             return err;
@@ -545,7 +637,7 @@ static BusState *qbus_find_recursive(BusState *bus, const char *name,
         return bus;
     }
 
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         QLIST_FOREACH(child, &dev->child_bus, sibling) {
             ret = qbus_find_recursive(child, name, info);
             if (ret) {
@@ -561,7 +653,7 @@ DeviceState *qdev_find_recursive(BusState *bus, const char *id)
     DeviceState *dev, *ret;
     BusState *child;
 
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         if (dev->id && strcmp(dev->id, id) == 0)
             return dev;
         QLIST_FOREACH(child, &dev->child_bus, sibling) {
@@ -594,7 +686,7 @@ static void qbus_list_dev(BusState *bus)
     const char *sep = " ";
 
     error_printf("devices at \"%s\":", bus->name);
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         error_printf("%s\"%s\"", sep, dev->info->name);
         if (dev->id)
             error_printf("/\"%s\"", dev->id);
@@ -625,17 +717,17 @@ static DeviceState *qbus_find_dev(BusState *bus, char *elem)
      *   (2) driver name
      *   (3) driver alias, if present
      */
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         if (dev->id  &&  strcmp(dev->id, elem) == 0) {
             return dev;
         }
     }
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         if (strcmp(dev->info->name, elem) == 0) {
             return dev;
         }
     }
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         if (dev->info->alias && strcmp(dev->info->alias, elem) == 0) {
             return dev;
         }
@@ -741,17 +833,17 @@ void qbus_create_inplace(BusState *bus, BusInfo *info,
 
     if (name) {
         /* use supplied name */
-        bus->name = qemu_strdup(name);
+        bus->name = g_strdup(name);
     } else if (parent && parent->id) {
         /* parent device has id -> use it for bus name */
         len = strlen(parent->id) + 16;
-        buf = qemu_malloc(len);
+        buf = g_malloc(len);
         snprintf(buf, len, "%s.%d", parent->id, parent->num_child_bus);
         bus->name = buf;
     } else {
         /* no id -> use lowercase bus type for bus name */
         len = strlen(info->name) + 16;
-        buf = qemu_malloc(len);
+        buf = g_malloc(len);
         len = snprintf(buf, len, "%s.%d", info->name,
                        parent ? parent->num_child_bus : 0);
         for (i = 0; i < len; i++)
@@ -759,7 +851,7 @@ void qbus_create_inplace(BusState *bus, BusInfo *info,
         bus->name = buf;
     }
 
-    QLIST_INIT(&bus->children);
+    QTAILQ_INIT(&bus->children);
     if (parent) {
         QLIST_INSERT_HEAD(&parent->child_bus, bus, sibling);
         parent->num_child_bus++;
@@ -774,17 +866,27 @@ BusState *qbus_create(BusInfo *info, DeviceState *parent, const char *name)
 {
     BusState *bus;
 
-    bus = qemu_mallocz(info->size);
+    bus = g_malloc0(info->size);
     bus->qdev_allocated = 1;
     qbus_create_inplace(bus, info, parent, name);
     return bus;
 }
 
+static void main_system_bus_create(void)
+{
+    /* assign main_system_bus before qbus_create_inplace()
+     * in order to make "if (bus != main_system_bus)" work */
+    main_system_bus = g_malloc0(system_bus_info.size);
+    main_system_bus->qdev_allocated = 1;
+    qbus_create_inplace(main_system_bus, &system_bus_info, NULL,
+                        "main-system-bus");
+}
+
 void qbus_free(BusState *bus)
 {
     DeviceState *dev;
 
-    while ((dev = QLIST_FIRST(&bus->children)) != NULL) {
+    while ((dev = QTAILQ_FIRST(&bus->children)) != NULL) {
         qdev_free(dev);
     }
     if (bus->parent) {
@@ -794,9 +896,9 @@ void qbus_free(BusState *bus)
         assert(bus != main_system_bus); /* main_system_bus is never freed */
         qemu_unregister_reset(qbus_reset_all_fn, bus);
     }
-    qemu_free((void*)bus->name);
+    g_free((void*)bus->name);
     if (bus->qdev_allocated) {
-        qemu_free(bus);
+        g_free(bus);
     }
 }
 
@@ -853,7 +955,7 @@ static void qbus_print(Monitor *mon, BusState *bus, int indent)
     qdev_printf("bus: %s\n", bus->name);
     indent += 2;
     qdev_printf("type %s\n", bus->info->name);
-    QLIST_FOREACH(dev, &bus->children, sibling) {
+    QTAILQ_FOREACH(dev, &bus->children, sibling) {
         qdev_print(mon, dev, indent);
     }
 }
@@ -916,7 +1018,7 @@ static int qdev_get_fw_dev_path_helper(DeviceState *dev, char *p, int size)
         if (dev->parent_bus->info->get_fw_dev_path) {
             d = dev->parent_bus->info->get_fw_dev_path(dev);
             l += snprintf(p + l, size - l, "%s", d);
-            qemu_free(d);
+            g_free(d);
         } else {
             l += snprintf(p + l, size - l, "%s", dev->info->name);
         }
@@ -937,3 +1039,499 @@ char* qdev_get_fw_dev_path(DeviceState *dev)
 
     return strdup(path);
 }
+
+char *qdev_get_type(DeviceState *dev, Error **errp)
+{
+    return g_strdup(dev->info->name);
+}
+
+void qdev_ref(DeviceState *dev)
+{
+    dev->ref++;
+}
+
+void qdev_unref(DeviceState *dev)
+{
+    g_assert(dev->ref > 0);
+    dev->ref--;
+}
+
+void qdev_property_add(DeviceState *dev, const char *name, const char *type,
+                       DevicePropertyAccessor *get, DevicePropertyAccessor *set,
+                       DevicePropertyRelease *release,
+                       void *opaque, Error **errp)
+{
+    DeviceProperty *prop = g_malloc0(sizeof(*prop));
+
+    prop->name = g_strdup(name);
+    prop->type = g_strdup(type);
+
+    prop->get = get;
+    prop->set = set;
+    prop->release = release;
+    prop->opaque = opaque;
+
+    QTAILQ_INSERT_TAIL(&dev->properties, prop, node);
+}
+
+static DeviceProperty *qdev_property_find(DeviceState *dev, const char *name)
+{
+    DeviceProperty *prop;
+
+    QTAILQ_FOREACH(prop, &dev->properties, node) {
+        if (strcmp(prop->name, name) == 0) {
+            return prop;
+        }
+    }
+
+    return NULL;
+}
+
+void qdev_property_get(DeviceState *dev, Visitor *v, const char *name,
+                       Error **errp)
+{
+    DeviceProperty *prop = qdev_property_find(dev, name);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, dev->id?:"", name);
+        return;
+    }
+
+    if (!prop->get) {
+        error_set(errp, QERR_PERMISSION_DENIED);
+    } else {
+        prop->get(dev, v, prop->opaque, name, errp);
+    }
+}
+
+void qdev_property_set(DeviceState *dev, Visitor *v, const char *name,
+                       Error **errp)
+{
+    DeviceProperty *prop = qdev_property_find(dev, name);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, dev->id?:"", name);
+        return;
+    }
+
+    if (!prop->set) {
+        error_set(errp, QERR_PERMISSION_DENIED);
+    } else {
+        prop->set(dev, v, prop->opaque, name, errp);
+    }
+}
+
+const char *qdev_property_get_type(DeviceState *dev, const char *name, Error **errp)
+{
+    DeviceProperty *prop = qdev_property_find(dev, name);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, dev->id?:"", name);
+        return NULL;
+    }
+
+    return prop->type;
+}
+
+/**
+ * Legacy property handling
+ */
+
+static void qdev_get_legacy_property(DeviceState *dev, Visitor *v, void *opaque,
+                                     const char *name, Error **errp)
+{
+    Property *prop = opaque;
+
+    char buffer[1024];
+    char *ptr = buffer;
+
+    prop->info->print(dev, prop, buffer, sizeof(buffer));
+    visit_type_str(v, &ptr, name, errp);
+}
+
+static void qdev_set_legacy_property(DeviceState *dev, Visitor *v, void *opaque,
+                                     const char *name, Error **errp)
+{
+    Property *prop = opaque;
+    Error *local_err = NULL;
+    char *ptr = NULL;
+    int ret;
+
+    if (dev->state != DEV_STATE_CREATED) {
+        error_set(errp, QERR_PERMISSION_DENIED);
+        return;
+    }
+
+    visit_type_str(v, &ptr, name, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    ret = prop->info->parse(dev, prop, ptr);
+    error_set_from_qdev_prop_error(errp, ret, dev, prop, ptr);
+    g_free(ptr);
+}
+
+/**
+ * @qdev_add_legacy_property - adds a legacy property
+ *
+ * Do not use this is new code!  Properties added through this interface will
+ * be given names and types in the "legacy" namespace.
+ *
+ * Legacy properties are always processed as strings.  The format of the string
+ * depends on the property type.
+ */
+void qdev_property_add_legacy(DeviceState *dev, Property *prop,
+                              Error **errp)
+{
+    gchar *name, *type;
+
+    name = g_strdup_printf("legacy-%s", prop->name);
+    type = g_strdup_printf("legacy<%s>",
+                           prop->info->legacy_name ?: prop->info->name);
+
+    qdev_property_add(dev, name, type,
+                      prop->info->print ? qdev_get_legacy_property : NULL,
+                      prop->info->parse ? qdev_set_legacy_property : NULL,
+                      NULL,
+                      prop, errp);
+
+    g_free(type);
+    g_free(name);
+}
+
+/**
+ * @qdev_property_add_static - add a @Property to a device.
+ *
+ * Static properties access data in a struct.  The actual type of the
+ * property and the field depends on the property type.
+ */
+void qdev_property_add_static(DeviceState *dev, Property *prop,
+                              Error **errp)
+{
+    qdev_property_add(dev, prop->name, prop->info->name,
+                      prop->info->get, prop->info->set,
+                      NULL,
+                      prop, errp);
+}
+
+DeviceState *qdev_get_root(void)
+{
+    static DeviceState *qdev_root;
+
+    if (!qdev_root) {
+        qdev_root = qdev_create(NULL, "container");
+        qdev_init_nofail(qdev_root);
+    }
+
+    return qdev_root;
+}
+
+static void qdev_get_child_property(DeviceState *dev, Visitor *v, void *opaque,
+                                    const char *name, Error **errp)
+{
+    DeviceState *child = opaque;
+    gchar *path;
+
+    path = qdev_get_canonical_path(child);
+    visit_type_str(v, &path, name, errp);
+    g_free(path);
+}
+
+void qdev_property_add_child(DeviceState *dev, const char *name,
+                             DeviceState *child, Error **errp)
+{
+    gchar *type;
+
+    type = g_strdup_printf("child<%s>", child->info->name);
+
+    qdev_property_add(dev, name, type, qdev_get_child_property,
+                      NULL, NULL, child, errp);
+
+    qdev_ref(child);
+    g_assert(child->parent == NULL);
+    child->parent = dev;
+
+    g_free(type);
+}
+
+static void qdev_get_link_property(DeviceState *dev, Visitor *v, void *opaque,
+                                   const char *name, Error **errp)
+{
+    DeviceState **child = opaque;
+    gchar *path;
+
+    if (*child) {
+        path = qdev_get_canonical_path(*child);
+        visit_type_str(v, &path, name, errp);
+        g_free(path);
+    } else {
+        path = (gchar *)"";
+        visit_type_str(v, &path, name, errp);
+    }
+}
+
+static void qdev_set_link_property(DeviceState *dev, Visitor *v, void *opaque,
+                                   const char *name, Error **errp)
+{
+    DeviceState **child = opaque;
+    bool ambiguous = false;
+    const char *type;
+    char *path;
+
+    type = qdev_property_get_type(dev, name, NULL);
+
+    visit_type_str(v, &path, name, errp);
+
+    if (*child) {
+        qdev_unref(*child);
+    }
+
+    if (strcmp(path, "") != 0) {
+        DeviceState *target;
+
+        target = qdev_resolve_path(path, &ambiguous);
+        if (target) {
+            gchar *target_type;
+
+            target_type = g_strdup_printf("link<%s>", target->info->name);
+            if (strcmp(target_type, type) == 0) {
+                *child = target;
+                qdev_ref(target);
+            } else {
+                error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, type);
+            }
+
+            g_free(target_type);
+        } else {
+            error_set(errp, QERR_DEVICE_NOT_FOUND, path);
+        }
+    } else {
+        *child = NULL;
+    }
+
+    g_free(path);
+}
+
+void qdev_property_add_link(DeviceState *dev, const char *name,
+                            const char *type, DeviceState **child,
+                            Error **errp)
+{
+    gchar *full_type;
+
+    full_type = g_strdup_printf("link<%s>", type);
+
+    qdev_property_add(dev, name, full_type,
+                      qdev_get_link_property,
+                      qdev_set_link_property,
+                      NULL, child, errp);
+
+    g_free(full_type);
+}
+
+gchar *qdev_get_canonical_path(DeviceState *dev)
+{
+    DeviceState *root = qdev_get_root();
+    char *newpath = NULL, *path = NULL;
+
+    while (dev != root) {
+        DeviceProperty *prop = NULL;
+
+        g_assert(dev->parent != NULL);
+
+        QTAILQ_FOREACH(prop, &dev->parent->properties, node) {
+            if (!strstart(prop->type, "child<", NULL)) {
+                continue;
+            }
+
+            if (prop->opaque == dev) {
+                if (path) {
+                    newpath = g_strdup_printf("%s/%s", prop->name, path);
+                    g_free(path);
+                    path = newpath;
+                } else {
+                    path = g_strdup(prop->name);
+                }
+                break;
+            }
+        }
+
+        g_assert(prop != NULL);
+
+        dev = dev->parent;
+    }
+
+    newpath = g_strdup_printf("/%s", path);
+    g_free(path);
+
+    return newpath;
+}
+
+static DeviceState *qdev_resolve_abs_path(DeviceState *parent,
+                                          gchar **parts,
+                                          int index)
+{
+    DeviceProperty *prop;
+    DeviceState *child;
+
+    if (parts[index] == NULL) {
+        return parent;
+    }
+
+    if (strcmp(parts[index], "") == 0) {
+        return qdev_resolve_abs_path(parent, parts, index + 1);
+    }
+
+    prop = qdev_property_find(parent, parts[index]);
+    if (prop == NULL) {
+        return NULL;
+    }
+
+    child = NULL;
+    if (strstart(prop->type, "link<", NULL)) {
+        DeviceState **pchild = prop->opaque;
+        if (*pchild) {
+            child = *pchild;
+        }
+    } else if (strstart(prop->type, "child<", NULL)) {
+        child = prop->opaque;
+    }
+
+    if (!child) {
+        return NULL;
+    }
+
+    return qdev_resolve_abs_path(child, parts, index + 1);
+}
+
+static DeviceState *qdev_resolve_partial_path(DeviceState *parent,
+                                              gchar **parts,
+                                              bool *ambiguous)
+{
+    DeviceState *dev;
+    DeviceProperty *prop;
+
+    dev = qdev_resolve_abs_path(parent, parts, 0);
+
+    QTAILQ_FOREACH(prop, &parent->properties, node) {
+        DeviceState *found;
+
+        if (!strstart(prop->type, "child<", NULL)) {
+            continue;
+        }
+
+        found = qdev_resolve_partial_path(prop->opaque, parts, ambiguous);
+        if (found) {
+            if (dev) {
+                if (ambiguous) {
+                    *ambiguous = true;
+                }
+                return NULL;
+            }
+            dev = found;
+        }
+
+        if (ambiguous && *ambiguous) {
+            return NULL;
+        }
+    }
+
+    return dev;
+}
+
+DeviceState *qdev_resolve_path(const char *path, bool *ambiguous)
+{
+    bool partial_path = true;
+    DeviceState *dev;
+    gchar **parts;
+
+    parts = g_strsplit(path, "/", 0);
+    if (parts == NULL || parts[0] == NULL) {
+        g_strfreev(parts);
+        return qdev_get_root();
+    }
+
+    if (strcmp(parts[0], "") == 0) {
+        partial_path = false;
+    }
+
+    if (partial_path) {
+        if (ambiguous) {
+            *ambiguous = false;
+        }
+        dev = qdev_resolve_partial_path(qdev_get_root(), parts, ambiguous);
+    } else {
+        dev = qdev_resolve_abs_path(qdev_get_root(), parts, 1);
+    }
+
+    g_strfreev(parts);
+
+    return dev;
+}
+
+typedef struct StringProperty
+{
+    char *(*get)(DeviceState *, Error **);
+    void (*set)(DeviceState *, const char *, Error **);
+} StringProperty;
+
+static void qdev_property_get_str(DeviceState *dev, Visitor *v, void *opaque,
+                                  const char *name, Error **errp)
+{
+    StringProperty *prop = opaque;
+    char *value;
+
+    value = prop->get(dev, errp);
+    if (value) {
+        visit_type_str(v, &value, name, errp);
+        g_free(value);
+    }
+}
+
+static void qdev_property_set_str(DeviceState *dev, Visitor *v, void *opaque,
+                                  const char *name, Error **errp)
+{
+    StringProperty *prop = opaque;
+    char *value;
+    Error *local_err = NULL;
+
+    visit_type_str(v, &value, name, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    prop->set(dev, value, errp);
+    g_free(value);
+}
+
+static void qdev_property_release_str(DeviceState *dev, const char *name,
+                                      void *opaque)
+{
+    StringProperty *prop = opaque;
+    g_free(prop);
+}
+
+void qdev_property_add_str(DeviceState *dev, const char *name,
+                           char *(*get)(DeviceState *, Error **),
+                           void (*set)(DeviceState *, const char *, Error **),
+                           Error **errp)
+{
+    StringProperty *prop = g_malloc0(sizeof(*prop));
+
+    prop->get = get;
+    prop->set = set;
+
+    qdev_property_add(dev, name, "string",
+                      get ? qdev_property_get_str : NULL,
+                      set ? qdev_property_set_str : NULL,
+                      qdev_property_release_str,
+                      prop, errp);
+}
+
+void qdev_machine_init(void)
+{
+    qdev_get_peripheral_anon();
+    qdev_get_peripheral();
+}