qdev/compat: compat property infrastructure.

This add support for switching devices into a compatibility mode
using device properties.  Machine types can have a list of properties
for specific devices attached to allow the easy creation of machine
types compatible to older qemu versions.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/boards.h

@@ -3,6 +3,8 @@
 #ifndef HW_BOARDS_H
 #define HW_BOARDS_H
 
+#include "qdev.h"
+
 typedef void QEMUMachineInitFunc(ram_addr_t ram_size,
                                  const char *boot_device,
                                  const char *kernel_filename,
@@ -17,6 +19,7 @@ typedef struct QEMUMachine {
     int use_scsi;
     int max_cpus;
     int is_default;
+    CompatProperty *compat_props;
     struct QEMUMachine *next;
 } QEMUMachine;
 

hw/qdev-properties.c

@@ -244,3 +244,26 @@ void qdev_prop_set_defaults(DeviceState *dev, Property *props)
     }
 }
 
+static CompatProperty *compat_props;
+
+void qdev_prop_register_compat(CompatProperty *props)
+{
+    compat_props = props;
+}
+
+void qdev_prop_set_compat(DeviceState *dev)
+{
+    CompatProperty *prop;
+
+    if (!compat_props) {
+        return;
+    }
+    for (prop = compat_props; prop->driver != NULL; prop++) {
+        if (strcmp(dev->info->name, prop->driver) != 0) {
+            continue;
+        }
+        if (qdev_prop_parse(dev, prop->property, prop->value) != 0) {
+            abort();
+        }
+    }
+}

hw/qdev.c

@@ -85,6 +85,7 @@ DeviceState *qdev_create(BusState *bus, const char *name)
     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_compat(dev);
     LIST_INSERT_HEAD(&bus->children, dev, sibling);
     return dev;
 }

hw/qdev.h

@@ -8,6 +8,8 @@ typedef struct Property Property;
 
 typedef struct PropertyInfo PropertyInfo;
 
+typedef struct CompatProperty CompatProperty;
+
 typedef struct DeviceInfo DeviceInfo;
 
 typedef struct BusState BusState;
@@ -68,6 +70,12 @@ struct PropertyInfo {
     int (*print)(DeviceState *dev, Property *prop, char *dest, size_t len);
 };
 
+struct CompatProperty {
+    const char *driver;
+    const char *property;
+    const char *value;
+};
+
 /*** Board API.  This should go away once we have a machine config file.  ***/
 
 DeviceState *qdev_create(BusState *bus, const char *name);
@@ -147,4 +155,7 @@ void qdev_prop_set_uint32(DeviceState *dev, const char *name, uint32_t value);
 void qdev_prop_set_ptr(DeviceState *dev, const char *name, void *value);
 void qdev_prop_set_defaults(DeviceState *dev, Property *props);
 
+void qdev_prop_register_compat(CompatProperty *props);
+void qdev_prop_set_compat(DeviceState *dev);
+
 #endif

vl.c

@@ -5946,6 +5946,9 @@ int main(int argc, char **argv, char **envp)
 
     module_call_init(MODULE_INIT_DEVICE);
 
+    if (machine->compat_props) {
+        qdev_prop_register_compat(machine->compat_props);
+    }
     machine->init(ram_size, boot_devices,
                   kernel_filename, kernel_cmdline, initrd_filename, cpu_model);