Re: [Qemu-devel] [RFC PATCH 09/13] memory: MemoryRegion: QOMify

[Paolo Bonzini]

Il 11/06/2014 15:12, Peter Crosthwaite ha scritto:
> > > +    if (name) {
> Should a stock "anonymous" or such name be used if !name?
>
> > > +        object_property_add_child_array(mr->owner, name, OBJECT(mr));

The !name case is used by "transient" memory regions for which we don't 
want the overhead of QOM (right now, this is the subpage memory regions 
used by exec.c).  These are removed with object_unref, not object_unparent.

Because of the default owner now being /machine, the problem becomes 
much more pervasive.

I tried a few machines, and even perfectly qdevified ones fail.  For 
example ARM has multiple gic_cpu memory regions.  And everything that 
has two instances of something that is not qdev-ified will fail horribly 
(this includes PC, whose 8257 DMA controllers are not qdev-ified).

If you do not create all memory region as children you cannot know how 
to destroy the region: will an unref be enough (memory_region_destroy in 
your series) or is unparent also necessary?

In the end, I believe the conceptual cleanliness of destroy==unparent, 
and the removal of 200-odd memory_region_destroy calls, are worth the 
extra ugly [0]'s.

Paolo