On 21/09/2018 18:00, Dr. David Alan Gilbert wrote: > * David Hildenbrand (da...@redhat.com) wrote: >> Compile virtio-pmem for x86 and properly hotplug virtio-pmem devices >> (memory-device part) from our pc machine hotplug handler. >> >> Signed-off-by: David Hildenbrand <da...@redhat.com> > > I see a few other places in the pc subdir that have checks for > TYPE_NVDIMM; can you just explain why they are untouched: > i386/pc.c: pc_memory_unplug_request
I think I had an answer why that isn't needed, but for unplug we might still be missing something. In general: unplug requests are always directed at the proxy device (via qdev_unplug()) (e.g. virtio-pmem-pci, see below). virtio-pmem is a child device of virtio-pmem-pci. Once virtio-pmem-pci is finally unrealized, the virtio-mem device will be unrealized. Now, there are no hotplug handlers getting called as far as I can see for that child device. there would have to be an proper call to a hotplug handler somewhere when setting the device to unrealized. (and that's the place where a unplug requests does not make really sense, but only a straight unplug - because we are half way through removing the hierarchy of devices - one of the reason why also failures of unrealize are usually ignored). I'll look into the details. Thanks for pointing that out, this stuff always messes with my head. > acpi/ich9.c: ich9_pm_device_plug_cb > acpi/piix4.c:piix4_device_plug_cb virtio-pmem is not an acpi device, that's why these don't apply. E.g. if virtio-pmem-pci is plugged, it will most probably trigger these hotplug handlers for the proxy virtio pci device. The proxy device creates and realized the virtio-mem (memory-device) - without any hotplug handlers involved. That#s the point where we can jump in and realize the device via the machine instead. > > (Not that I understand the detail of those paths, but I just > followed where the existing nvdimm code goes) > > Dave -- Thanks, David / dhildenb
