qdev: Display warning about unused -global

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>
Acked-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 404cf1843d..de433b2e38 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -439,11 +439,27 @@ PropertyInfo qdev_prop_iothread = {
 static int qdev_add_one_global(QemuOpts *opts, void *opaque)
 {
     GlobalProperty *g;
+    ObjectClass *oc;
 
     g = g_malloc0(sizeof(*g));
     g->driver   = qemu_opt_get(opts, "driver");
     g->property = qemu_opt_get(opts, "property");
     g->value    = qemu_opt_get(opts, "value");
+    oc = object_class_by_name(g->driver);
+    if (oc) {
+        DeviceClass *dc = DEVICE_CLASS(oc);
+
+        if (dc->hotpluggable) {
+            /* If hotpluggable then skip not_used checking. */
+            g->not_used = false;
+        } else {
+            /* Maybe a typo. */
+            g->not_used = true;
+        }
+    } else {
+        /* Maybe a typo. */
+        g->not_used = true;
+    }
     qdev_prop_register_global(g);
     return 0;
 }