softmmu/vl.c: Disable default NIC if it has not been compiled into th…

…e binary

Don't try to instantiate a default NIC if it is not available (since
this will cause QEMU to abort). Emit a warning instead.

Message-Id: <20230512124033.502654-5-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

softmmu/vl.c

@@ -1294,6 +1294,13 @@ static void qemu_disable_default_devices(void)
         default_monitor = 0;
         default_net = 0;
         default_vga = 0;
+    } else {
+        if (default_net && machine_class->default_nic &&
+            !module_object_class_by_name(machine_class->default_nic)) {
+            warn_report("Default NIC '%s' is not available in this binary",
+                        machine_class->default_nic);
+            default_net = 0;
+        }
     }
 }