Re: QOM address space handling

[Eduardo Habkost]

On Tue, Nov 10, 2020 at 04:08:16PM +0100, Paolo Bonzini wrote:
> On 10/11/20 16:03, Eduardo Habkost wrote:
> > > Does anyone have any arguments for which solution is preferred?
> > I'd say (2) is preferred, as we don't expect object_new(T) to
> > have any side effects outside the object instance state.
> 
> Since there are no listeners, the side effects of address_space_init() are
> relatively limited.  So doing it in instance_init is not a big deal.
> 
> > Most
> > address_space_init() calls in the code today seem to be in
> > realize functions.
> > 
> > However, I wonder if we could make this simpler (and mistakes
> > less fatal) if we make AddressSpace a QOM child of the device.
> > Paolo, would it be too much overhead to make AddressSpace a QOM
> > object?
> 
> No, it wouldn't.  AddressSpace is already quite heavyweight.

I thought this was going to be an easy job, but call_rcu()
requires rcu_head to be the first struct field.  I assume it is
acceptable to use call_rcu1() + container_of() manually in this
case.

-- 
Eduardo