[PATCH v2 1/7] 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 if needed.  This patch adds it.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/hw/qdev-core.h |  3 +++
 include/qemu/module.h  |  1 +
 hw/core/qdev.c         | 50 ++++++++++++++++++++++++++++++++++++++++++
 qdev-monitor.c         |  5 +++++
 qom/qom-qmp-cmds.c     |  1 +
 stubs/hw-module.c      |  6 +++++
 stubs/Makefile.objs    |  1 +
 7 files changed, 67 insertions(+)
 create mode 100644 stubs/hw-module.c

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..7177798840d4 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -146,10 +146,60 @@ 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;
+
+    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;
+
+    if (qdev_module_loaded_all) {
+        return;
+    }
+    for (i = 0; i < ARRAY_SIZE(hwmodules); i++) {
+        if (i > 0 && strcmp(hwmodules[i - 1].mod,
+                            hwmodules[i].mod) == 0) {
+            /* one module implementing multiple devices -> load only once */
+            continue;
+        }
+        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) {
diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
index c5249e44d020..fe48cd2f9cf0 100644
--- a/qom/qom-qmp-cmds.c
+++ b/qom/qom-qmp-cmds.c
@@ -116,6 +116,7 @@ ObjectTypeInfoList *qmp_qom_list_types(bool has_implements,
 {
     ObjectTypeInfoList *ret = NULL;
 
+    qdev_module_load_all();
     object_class_foreach(qom_list_types_tramp, implements, abstract, &ret);
 
     return ret;
diff --git a/stubs/hw-module.c b/stubs/hw-module.c
new file mode 100644
index 000000000000..1c312d2fc2b3
--- /dev/null
+++ b/stubs/hw-module.c
@@ -0,0 +1,6 @@
+#include "qemu/osdep.h"
+#include "hw/qdev-core.h"
+
+void qdev_module_load_all(void)
+{
+}
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 6a9e3135e8f9..a4eb96514ddc 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -44,4 +44,5 @@ stub-obj-y += pci-host-piix.o
 stub-obj-y += ram-block.o
 stub-obj-y += ramfb.o
 stub-obj-y += fw_cfg.o
+stub-obj-y += hw-module.o
 stub-obj-$(CONFIG_SOFTMMU) += semihost.o
-- 
2.18.4