On Fri, Jan 12, 2018 at 10:23 PM, Pankaj Gupta <pagupta@xxxxxxxxxx> wrote: > > Hello Dan, > >> Not a flag, but a new "Address Range Type GUID". See section "5.2.25.2 >> System Physical Address (SPA) Range Structure" in the ACPI 6.2A >> specification. Since it is a GUID we could define a Linux specific >> type for this case, but spec changes would allow non-Linux hypervisors >> to advertise a standard interface to guests. >> > > I have added new SPA with a GUUID for this memory type and I could add > this new memory type in System memory map. I need help with the namespace > handling for this new type As mentioned in [1] discussion: > > - Create a new namespace for this new memory type > - Teach libnvdimm how to handle this new namespace > > I have some queries on this: > > 1] How namespace handling of this new memory type would be? This would be a namespace that creates a pmem device, but does not allow DAX. > > 2] There are existing namespace types: > ND_DEVICE_NAMESPACE_IO, ND_DEVICE_NAMESPACE_PMEM, ND_DEVICE_NAMESPACE_BLK > > How libnvdimm will handle this new name-space type in conjuction with existing > memory type, region & namespaces? The type will be either ND_DEVICE_NAMESPACE_IO or ND_DEVICE_NAMESPACE_PMEM depending on whether you configure KVM to provide a virtual NVDIMM and label space. In other words the only difference between this range and a typical persistent memory range is that we will have a flag to disable DAX operation. See the usage of nvdimm_has_cache() in pmem_attach_disk() as an example of how to pass attributes about the "region" to the the pmem driver. > > 3] For sending guest to host flush commands we still have to think about some > async way? I thought we discussed this being a paravirtualized virtio command ring?
