Re: Dynamic instance properties in TYPE_ARM_CPU

[Andrew Jones]

On Mon, Oct 26, 2020 at 01:22:19PM -0400, Eduardo Habkost wrote:
> I've been trying to clean up the qdev property code (to bridge
> the gaps between qdev and QOM, and between QOM and QAPI), and
> I've noticed that TYPE_ARM_CPU is the only remaining user of
> qdev_property_add_static().
> 
> qdev_property_add_static() has a misleading name: it won't
> register a static property.  It is actually a hack to use a
> static Property variable (defined using DEFINE_PROP*), but
> register it as a dynamic instance property.
> 
> Dynamic instance properties make introspection hard.  What can we
> do to get rid of them in TYPE_ARM_CPU?
> 
> Can we just register all the properties unconditionally, and
> error out on realize if the requested CPU configuration is
> incompatible with the available CPU features?
> 
> The following properties are registered as dynamic instance
> properties at arm_cpu_post_init():
> "cntfrq", "reset-cbar", "reset-hivecs", "rvbar", "has_el2",
> "has_el3", "cfgend", "vfp", "neon", "dsp", "has-mpu",
> "pmsav7-dregion", "secure-memory", "pmu", "idau", "init-svtor",
> "tag-memory", "secure-tag-memory".

Hi Eduardo,

Are properties added at runtime with

  if (this_config_wants_this_property)
    object_property_add(...)

also considered dynamic instance properties? If so, then
arm as many more than the ones listed above. And, if not,
then it should be pretty easy to convert the ones listed
above to this if-want-add pattern.

Thanks,
drew