[PATCH 1/2] qdev: add support for device module loading

[Gerd Hoffmann <kraxel@redhat.com>]

When compiling devices as modules we'll need some infrastrtucture to
actually load those modules.  This patch adds it.

FIXME: Probably need to sprinkle a qdev_module_load_all() call somewhere
into monitor code to make QOM introspection work properly for modular
devices.  Didn't manage yet to find the place.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/hw/qdev-core.h |  3 +++
 include/qemu/module.h  |  1 +
 hw/core/qdev.c         | 47 ++++++++++++++++++++++++++++++++++++++++++
 qdev-monitor.c         |  5 +++++
 4 files changed, 56 insertions(+)

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index b870b279661a..a96c890bb95b 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -552,4 +552,7 @@ void device_listener_unregister(DeviceListener *listener);
  */
 bool qdev_should_hide_device(QemuOpts *opts);
 
+void qdev_module_load_type(const char *type);
+void qdev_module_load_all(void);
+
 #endif
diff --git a/include/qemu/module.h b/include/qemu/module.h
index 011ae1ae7605..077a6b09bca7 100644
--- a/include/qemu/module.h
+++ b/include/qemu/module.h
@@ -64,6 +64,7 @@ typedef enum {
 #define block_module_load_one(lib) module_load_one("block-", lib)
 #define ui_module_load_one(lib) module_load_one("ui-", lib)
 #define audio_module_load_one(lib) module_load_one("audio-", lib)
+#define hw_module_load_one(lib) module_load_one("hw-", lib)
 
 void register_module_init(void (*fn)(void), module_init_type type);
 void register_dso_module_init(void (*fn)(void), module_init_type type);
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 9e5538aeaebd..20e5c4cbafd8 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -146,10 +146,57 @@ DeviceState *qdev_create(BusState *bus, const char *name)
     return dev;
 }
 
+/*
+ * Building devices modular is mostly useful in case they have
+ * dependencies to external libraries.  Which is the case for very few
+ * devices.  So with the expecration that this will be rather the
+ * exception than to rule go with a simple hardcoded list for now ...
+ */
+static struct {
+    const char *type;
+    const char *mod;
+} const hwmodules[] = {
+};
+
+static bool qdev_module_loaded_all;
+
+void qdev_module_load_type(const char *type)
+{
+    int i;
+
+    fprintf(stderr, "%s: %s\n", __func__, type);
+    if (qdev_module_loaded_all) {
+        return;
+    }
+    for (i = 0; i < ARRAY_SIZE(hwmodules); i++) {
+        if (strcmp(hwmodules[i].type, type) == 0) {
+            hw_module_load_one(hwmodules[i].mod);
+            return;
+        }
+    }
+}
+
+void qdev_module_load_all(void)
+{
+    int i;
+
+    fprintf(stderr, "%s\n", __func__);
+    if (qdev_module_loaded_all) {
+        return;
+    }
+    for (i = 0; i < ARRAY_SIZE(hwmodules); i++) {
+        hw_module_load_one(hwmodules[i].mod);
+    }
+    qdev_module_loaded_all = true;
+}
+
 DeviceState *qdev_try_create(BusState *bus, const char *type)
 {
     DeviceState *dev;
 
+    if (object_class_by_name(type) == NULL) {
+        qdev_module_load_type(type);
+    }
     if (object_class_by_name(type) == NULL) {
         return NULL;
     }
diff --git a/qdev-monitor.c b/qdev-monitor.c
index a4735d3bb190..55dddeb2f978 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -147,6 +147,7 @@ static void qdev_print_devinfos(bool show_no_user)
     int i;
     bool cat_printed;
 
+    qdev_module_load_all();
     list = object_class_get_list_sorted(TYPE_DEVICE, false);
 
     for (i = 0; i <= DEVICE_CATEGORY_MAX; i++) {
@@ -224,6 +225,10 @@ static DeviceClass *qdev_get_device_class(const char **driver, Error **errp)
             oc = object_class_by_name(*driver);
         }
     }
+    if (!oc) {
+        qdev_module_load_type(*driver);
+        oc = object_class_by_name(*driver);
+    }
 
     if (!object_class_dynamic_cast(oc, TYPE_DEVICE)) {
         if (*driver != original_name) {
-- 
2.18.4