On Wed, 25 Apr 2018 16:54:12 +0530 Pankaj Gupta <pagupta@xxxxxxxxxx> wrote: [...] > - Qemu virtio-pmem device > It exposes a persistent memory range to KVM guest which > at host side is file backed memory and works as persistent > memory device. In addition to this it provides virtio > device handling of flushing interface. KVM guest performs > Qemu side asynchronous sync using this interface. a random high level question, Have you considered using a separate (from memory itself) virtio device as controller for exposing some memory, async flushing. And then just slaving pc-dimm devices to it with notification/ACPI code suppressed so that guest won't touch them? That way it might be more scale-able, you consume only 1 PCI slot for controller vs multiple for virtio-pmem devices. > Changes from previous RFC[1]: > > - Reuse existing 'pmem' code for registering persistent > memory and other operations instead of creating an entirely > new block driver. > - Use VIRTIO driver to register memory information with > nvdimm_bus and create region_type accordingly. > - Call VIRTIO flush from existing pmem driver. > > Details of project idea for 'fake DAX' flushing interface is > shared [2] & [3]. > > Pankaj Gupta (2): > Add virtio-pmem guest driver > pmem: device flush over VIRTIO > > [1] https://marc.info/?l=linux-mm&m=150782346802290&w=2 > [2] https://www.spinics.net/lists/kvm/msg149761.html > [3] https://www.spinics.net/lists/kvm/msg153095.html > > drivers/nvdimm/region_devs.c | 7 ++ > drivers/virtio/Kconfig | 12 +++ > drivers/virtio/Makefile | 1 > drivers/virtio/virtio_pmem.c | 118 +++++++++++++++++++++++++++++++++++++++ > include/linux/libnvdimm.h | 4 + > include/uapi/linux/virtio_ids.h | 1 > include/uapi/linux/virtio_pmem.h | 58 +++++++++++++++++++ > 7 files changed, 201 insertions(+) >
