Re: [PATCH v2 2/2] spapr: use DEVICE_UNPLUG_ERROR to report unplug errors

[Eric Blake]

On Wed, Jun 16, 2021 at 01:58:04PM -0300, Daniel Henrique Barboza wrote:
> > Incompatible change: we now emit DEVICE_UNPLUG_ERROR instead of
> > MEM_UNPLUG_ERROR.  Intentional?
> > 
> > If yes, we need a release note.
> > 
> > To avoid the incompatible, we can emit both, and deprecate
> > MEM_UNPLUG_ERROR.
> > 
> > What about the MEM_UNPLUG_ERROR in acpi_memory_hotplug_write()?
> 
> I'll emit DEVICE_UNPLUG_ERROR together with all MEM_UNPLUG_ERROR instances.
> Then we can deprecate MEM_UNPLUG_ERROR.
> 
> By the way, how do I mark MEM_UNPLUG_ERROR as deprecated? I see examples
> of command line options being documented as deprecated in
> docs/system/deprecated.rst and some deprecated QOM/QDEV properties are
> marked as deprecated directly in their .json files, but I didn't find
> any case where a whole event is deprecated. Would something like this be
> adequate?

Almost.  That documents the deprecation for readers, but you also need
to mark it for viewing by machine code...

> 
> 
> $ git diff
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 58a9c86b36..ce3d873c64 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -1261,6 +1261,10 @@
>  #
>  # @msg: Informative message
>  #
> +#
> +# @deprecated: Starting in 6.1 this event has been replaced by
> +#              DEVICE_UNPLUG_ERROR.
> +#
>  # Since: 2.4
>  #
>  # Example:

...do that by adding 'features':['deprecated'] to the QAPI event
definition.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org