On 12/03/21 10:31, Claudio Fontana wrote:
Hello Paolo and all,while debugging a class init ordering issue, I noticed that _all_ class init functions for all types registered in the QEMU QOM are called in select_machine(). Expected? In particular it happens here: static MachineClass *select_machine(void) { GSList *machines = object_class_get_list(TYPE_MACHINE, false); object_class_get_list() -> object_class_foreach() -> g_hash_table_foreach() -> object_class_foreach_tramp -> type_initialize(type); Is this really desired? It looks suspect to me.
It is not a problem because class_init should be idempotent. Changing QEMU to not do this would not be impossible, but most likely not worth the effort. To do this, I think one would have to reimplement all of object_class_dynamic_cast to operate on TypeInfos (so for example walk all interfaces in the type info instead of using class->interfaces).
If not here, where should be the right place, for example, for CPU class inits to be called?
The first time they're used, upon a call to one of object_new, object_initialize, object_class_get_list or object_class_foreach.
At the very least I would put a comment there around the beginning of select_machine() saying: /* all types, all classes in QOM are initialized here, as a result of the object_class_get_list call */
No, it's just a side effect that is not (or should not) be visible. Paolo
