On 23.04.2018 14:31, Igor Mammedov wrote: > On Fri, 20 Apr 2018 14:34:53 +0200 > David Hildenbrand <da...@redhat.com> wrote: > >> Right now we can only map PCDIMM/NVDIMM into guest address space. In the >> future, we might want to do the same for virtio devices - e.g. >> virtio-pmem or virtio-mem. Especially, they should be able to live side >> by side to each other. >> >> E.g. the virto based memory devices regions will not be exposed via ACPI >> and friends. They will be detected just like other virtio devices and >> indicate the applicable memory region. This makes it possible to also use >> them on architectures without memory device detection support (e.g. s390x). >> >> Let's factor out the memory device code into a MemoryDevice interface. > A couple of high level questions as relevant code is not here:
Important remark first: We also have s390x with virtio-ccw. This essentially will also allow s390x guests to have - memory hotplug via virtio-mem - fake dax devices via virtio-pmem > > 1. what would hotplug/unplug call chain look like in case of virtio-pmem > device > (reason I'm asking is that pmem being PCI device would trigger > PCI bus hotplug controller and then it somehow should piggyback > to Machine provided hotplug handlers, so I wonder what kind of > havoc it would cause on hotplug infrastructure) > > 2. why not use PCI bar mapping mechanism to do mapping since pmem is PCI > device? pmem might be a PCI device, but virtio-pmem is a virtio device (however it will be exposed via a proxy) > I think both questions are best answered by Pankaj (already on CC). -- Thanks, David / dhildenb
