On Mon, 13 Jul 2026 at 17:50, Richard Henderson <[email protected]> wrote: > > On 7/11/26 15:34, Alexander Graf wrote: > > We already have two ways of creating a QOM object with a parent set > > from birth: object_initialize_child() for objects embedded in the > > parent struct, and object_new_with_props() for heap-allocated objects > > that also want a list of string properties applied. What we do not > > have is the plain heap-allocated dual of object_initialize_child(): > > create the object, add it as a child<> of a given parent under a given > > name, and hand the reference to the parent. > > > > Board and composite-device code that heap-allocates children today > > therefore either open-codes object_new()+object_property_add_child() > > +object_unref(), or skips the parenting step entirely and lets > > device_set_realized() dump the object into /machine/unattached. > > > > Add object_new_child(parent, id, typename) as that missing primitive. > > The reference created by object_new() is transferred to the parent's > > child<> property, so on return the sole reference is held by @parent > > and the caller does not need to unref. Later patches build the qdev > > and per-bus creation helpers on top of this. > > > > Suggested-by: Markus Armbruster <[email protected]> > > Link: https://lore.kernel.org/qemu-devel/[email protected]/ > > Assisted-by: Kiro > > Signed-off-by: Alexander Graf <[email protected]> > > --- > > include/qom/object.h | 25 +++++++++++++++++++++++++ > > qom/object.c | 13 +++++++++++++ > > 2 files changed, 38 insertions(+) > > Reviewed-by: Richard Henderson <[email protected]> > > > +Object *object_new_child(Object *parent, const char *id, > > + const char *typename) > > +{ > > + Object *obj; > > + > > + g_assert(parent); > > + g_assert(id); > > Of course, typename can't be null either.
These asserts are of the "not very useful" kind, as well -- if either of these are NULL we're going to crash pretty quickly, and then the debugger backtrace will point you at your programming error. Asserts are most useful when they turn non-obvious bugs into obvious bugs or turn "happens a long time later than when the problem is" bugs into "happens very close to when the problem is". bugs. -- PMM
