On Wed, Jun 28, 2017 at 03:15:44PM +0800, Peter Xu wrote:
> It'll be strange that the migration object inherits TYPE_DEVICE. Add
> some explanations to it.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> migration/migration.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index b1b0825..2398a9d 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2046,6 +2046,14 @@ static void migration_instance_init(Object *obj)
>
> static const TypeInfo migration_type = {
> .name = TYPE_MIGRATION,
> + /*
> + * NOTE: "migration" itself is not really a device. We used
I suggest extending this as:
TYPE_MIGRATION is not really a device, as the object is not created
using qdev_create(), it is not attached to the qdev device tree, and
it is never realized.
> + * TYPE_DEVICE here only to leverage some existing QDev features
> + * like "-global" properties, and HW_COMPAT_* fields (which are
> + * finally applied as global properties as well). If one day the
> + * global property feature can be migrated from QDev to QObject in
> + * general, then we can switch to QObject as well.
> + */
QOM objects (qom/object.h) are not QObject (qapi/qmp/qobject.h). People
often confuse them with each other. (It probably doesn't help that both
are described as "QEMU Object Model" at their headers.)
I suggest rewriting it as:
If one day we allow non-device QOM objects to use the global property
system, we can switch this from TYPE_DEVICE to TYPE_OBJECT."
> .parent = TYPE_DEVICE,
> .class_init = migration_class_init,
> .class_size = sizeof(MigrationClass),
> --
> 2.7.4
>
--
Eduardo
