* David Hildenbrand (da...@redhat.com) wrote: > 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.
Does not being an acpi-device make life easier or harder? Again, not knowing anything about the pmem acpi; if it looked like a normal nvdimm through ACPI would OSs be able to boot off it? Dave > > > > (Not that I understand the detail of those paths, but I just > > followed where the existing nvdimm code goes) > > > > Dave > > > -- > > Thanks, > > David / dhildenb -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
