Re: [Qemu-devel] [PATCH 23/35] acpi:piix4: make plug/unlug callbacks generic

[Michael S. Tsirkin]

On Tue, Apr 29, 2014 at 10:12:34AM +0200, Paolo Bonzini wrote:
> Il 07/04/2014 17:36, Michael S. Tsirkin ha scritto:
> >>>  * What if there would be more handlers that could or should handle event
> >>>    for device?
> >That's actually very useful. We could scan top to bottom
> >so e.g. acpi can intercept bridges.
> >
> 
> Be careful about "top to bottom".  Does top-to-bottom mean by bus or
> by composition?  This has been a huge can of worms in the
> discussions about recursive realization.
> 
> One thing we could do is to always go through /machine even before
> invoking the bus handler.  Then /machine can do machine-specific
> checks to interpose the PCI host bridge and/or the ACPI device's
> hotplug handlers.
> 
> But this can be done on top of this series, it has nothing to do
> with memory hotplug and this one is already big enough!
> 
> Paolo

Yes, new functionality does not need to be added in this patchset.

But to repeat what I was saying, this check (that object passed in
is a PCI DEVICE) belongs in acpi_pcihp_device_plug_cb and should not be
piix specific, I don't want to duplicate this logic in q35 later.
Similar checks should be added in
shpc_device_hotplug_cb pcie_cap_slot_hotplug_cb for consistency.



-- 
MST