Re: [Qemu-devel] [PATCH v2 0/3] PCDIMM cleanup

[Igor Mammedov]

On Sat, 23 Feb 2019 00:02:49 +0000
Wei Yang <address@hidden> wrote:

> On Thu, Feb 21, 2019 at 03:50:04PM +0100, Igor Mammedov wrote:
> >On Wed, 20 Feb 2019 08:51:21 +0800
> >Wei Yang <address@hidden> wrote:
> >
> >> Three trivial cleanup for pc-dimm.
> >> 
> >> Patch [1] remove the check on class->hotpluggable since pc-dimm is always
> >> hotpluggable.
> >> Patch [2] remove nvdimm_realize
> >> Patch [2] remove pcdimm realize-callback
> >even though this series doesn't break anything, I disagree with it
> >conceptually as it makes device less abstracted and make it more
> >dependent on how existing machine code uses it.
> >I'd drop whole series.
> >
> 
> Is Patch [1] also make device more dependent on existing implementation?
yes, it's implementation detail that PCDIMM&Co are hotpluggable now.

> For example, when we look at the counterpart of acpi_memory_plug_cb():
> 
>     acpi_pcihp_device_plug_cb
> 
> which handle the pci device hotplug. We don't check the hotpluggable
> property for pci devices.
> 
> To me, this is a general rule for PCDIMM, they are hotpluggable.
yes, PCDIMMs are hotpluggable but apci device (piix4pm/ich9/...) handling 
hotplug
should ignore any non-hotpluggable one. If you remove check and then later
someone else would add non-hotpluggable memory device or make PC-DIMMs or its
variant of non-hotpluggable one, acpi device handling will break.
Hence I'd prefer to keep the check.  
 
> For Patch[2][3], I agree with you.
>