Re: [Qemu-arm] [PATCH 1/5] qom/object: Add a new function object_initialize_as_child()

[Paolo Bonzini]

On 12/07/2018 19:09, Peter Maydell wrote:
>> That's the same what object_initialize() is doing (see above). Otherwise
>> all the callers have to cast their pointers with OBJECT() first.
> Casting with OBJECT() would not work, because it does a typecheck.
> At the point where something is calling object_initialize() or
> object_initialize_with_child(), the memory at 'childobj' has not
> been initialized, so a typecheck is impossible.
> 
> It's only once the object has actually been initialized that
> the memory is a valid Object* that you can put through OBJECT().

OBJECT is special and just does a cast, because every pointer to a QOM
object would pass.  However, your reasoning still applies: you should
not put through OBJECT() an object that hasn't been initialized yet,
just like you should not put it through DEVICE() or any of the macros
that _do_ perform the typecheck.

Paolo