Re: [Qemu-devel] [PATCH 2/5] hw/ppc: removing spapr_drc_detach_cb opaques

[Laurent Vivier]

On 30/04/2017 19:25, Daniel Henrique Barboza wrote:
> Following up the previous detach_cb change, this patch removes the
> detach_cb_opaque entirely from the code.
> 
> The reason is that the drc->detach_cb_opaque object can't be
> restored in the post load of the upcoming DRC migration and no detach
> callbacks actually need this opaque. 'spapr_core_release' is
> receiving it as NULL, 'spapr_phb_remove_pci_device_cb' is receiving
> a phb object as opaque but is't using it. These were trivial removal
> cases.
> 
> However, the LM removal callback 'spapr_lmb_release' is receiving
> and using the opaque object, a 'sPAPRDIMMState' struct. This struct
> holds the number of LMBs the DIMM object contains and the callback
> was using this counter as a countdown to check if all LMB DRCs were
> release before proceeding to the DIMM unplug. To remove the need of
> this callback we have choices such as:
> 
> - migrate the 'sPAPRDIMMState' struct. This would require creating a
> QTAILQ to store all DIMMStates and an additional 'dimm_id' field to
> associate the DIMMState with the DIMM object. We could attach this
> QTAILQ to the 'sPAPRPHBState' and retrieve it later in the callback.
> 

Did you think about adding the nr_lmbs into PCDIMMDevice structure?
Or to create a SPAPRPCDIMMDevice with PCDIMMDevice parent_obj and
nr_lmbs field we can retrieve from the DeviceState pointer?

I don't know if it is a good idea or an acceptable way to do that, but
I'd like to know if you have thought about that.

Thanks,
Laurent