Re: [PATCH v2 14/21] hw/core/qdev-properties: allow qdev properties accept flags

[Zhao Liu <zhao1.liu@intel.com>]

(Sorry for the long silence — just returned from vacation.)

> > Yeah, most property setting paths are covered by
> > object_set_properties_from_qdict() (I listes these cases in patch 12,
> > including the most common ones: -object/-device and their related HMP/QMP
> > commands).
> > 
> > But there're some corner cases which don't go through
> > object_set_properties_from_qdict(), e.g., -global/-accel/"qom-set", etc,
> > those were considerred in patch 9/11/13 (and sorry I should list all
> > cases affected in cover letter :(). These cases are where I find
> > things to be both trivial and tricky, so I manually check them and mark
> > them using USER_SET.
> > 
> > Therefore, I think the unified entry point for externally setting
> > properties resides at a lower level—specifically, is object_property_set(),
> > then we need to dientify when object_property_set() is called by
> > external user or not - that's how USER_SET works...(I feel like I'm back
> > where I started).
> 
> There's a significant different there.  Emitting deprecation messages
> in the API entry points tied to user data is a clear purpose, not
> open to abuse. Recording the difference between user set & internally
> set against the object instance persistently is an open ended purpose
> and based on what we've seen in QEMU in the past, that is highly likely
> to be mis-used.
>
> The idea of supporting deprecations on properties is definitely
> something we should do, but I really dn't want to see that expressed
> via the 'user set' mechanism from this series.

Thank you for your explanation. In practice, as the alternative to
USER_SET, I understand we identify the specific API entry points (including
object_set_properties_from_qdict and others) and trigger the warning
directly within those functions / code path, may I ask if this
understanding is right?

The current API entry points are somewhat fragmented; perhaps we should
consider whether further unification is possible.

Regards,
Zhao