[PATCH v2 2/4] GlobalProperty: Display warning about unused -global

[Don Slutz <dslutz@verizon.com>]

This can help a user understand why -global was ignored.

For example: with "-vga cirrus"; "-global vga.vgamem_mb=16" is just
ignored when "-global cirrus-vga.vgamem_mb=16" is not.

This is currently clear when the wrong property is provided:

out/x86_64-softmmu/qemu-system-x86_64 -global cirrus-vga.vram_size_mb=16 -monitor pty -vga cirrus
char device redirected to /dev/pts/20 (label compat_monitor0)
qemu-system-x86_64: Property '.vram_size_mb' not found
Aborted (core dumped)

vs

out/x86_64-softmmu/qemu-system-x86_64 -global vga.vram_size_mb=16 -monitor pty -vga cirrus
char device redirected to /dev/pts/20 (label compat_monitor0)
VNC server running on `::1:5900'
^Cqemu: terminating on signal 2

Signed-off-by: Don Slutz <dslutz@verizon.com>
---
 hw/core/qdev-properties-system.c |  1 +
 hw/core/qdev-properties.c        | 15 +++++++++++++++
 include/hw/qdev-core.h           |  1 +
 include/hw/qdev-properties.h     |  1 +
 vl.c                             |  2 ++
 5 files changed, 20 insertions(+)

diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 5f5957e..6cc13a1 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -390,6 +390,7 @@ static int qdev_add_one_global(QemuOpts *opts, void *opaque)
     g->driver   = qemu_opt_get(opts, "driver");
     g->property = qemu_opt_get(opts, "property");
     g->value    = qemu_opt_get(opts, "value");
+    g->not_used = true;
     qdev_prop_register_global(g);
     return 0;
 }
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 77d0c66..d28d86e 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -939,6 +939,20 @@ void qdev_prop_register_global_list(GlobalProperty *props)
     }
 }
 
+void qdev_prop_check_global(void)
+{
+    GlobalProperty *prop;
+
+    QTAILQ_FOREACH(prop, &global_props, next) {
+        if (!prop->not_used) {
+            continue;
+        }
+        fprintf(stderr, "Warning: \"-global %s.%s=%s\" not used\n",
+                prop->driver, prop->property, prop->value);
+
+    }
+}
+
 void qdev_prop_set_globals_for_type(DeviceState *dev, const char *typename,
                                     Error **errp)
 {
@@ -950,6 +964,7 @@ void qdev_prop_set_globals_for_type(DeviceState *dev, const char *typename,
         if (strcmp(typename, prop->driver) != 0) {
             continue;
         }
+        prop->not_used = false;
         object_property_parse(OBJECT(dev), prop->value, prop->property, &err);
         if (err != NULL) {
             error_propagate(errp, err);
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 1ed0691..211f383 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -229,6 +229,7 @@ typedef struct GlobalProperty {
     const char *driver;
     const char *property;
     const char *value;
+    bool not_used;
     QTAILQ_ENTRY(GlobalProperty) next;
 } GlobalProperty;
 
diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h
index 0c0babf..6ef30b3 100644
--- a/include/hw/qdev-properties.h
+++ b/include/hw/qdev-properties.h
@@ -177,6 +177,7 @@ void qdev_prop_set_ptr(DeviceState *dev, const char *name, void *value);
 
 void qdev_prop_register_global(GlobalProperty *prop);
 void qdev_prop_register_global_list(GlobalProperty *props);
+void qdev_prop_check_global(void);
 void qdev_prop_set_globals(DeviceState *dev, Error **errp);
 void qdev_prop_set_globals_for_type(DeviceState *dev, const char *typename,
                                     Error **errp);
diff --git a/vl.c b/vl.c
index bca5c95..63794fc 100644
--- a/vl.c
+++ b/vl.c
@@ -4411,6 +4411,8 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    qdev_prop_check_global();
+
     if (incoming) {
         Error *local_err = NULL;
         qemu_start_incoming_migration(incoming, &local_err);
-- 
1.8.4