---
features:
  - |
    Add nova file_backed_memory and memory_backing_dir support for qemu.conf

    The libvirt driver now allows utilizing file backed memory for qemu/KVM
    virtual machines, via a new configuration attribute
    ``[libvirt]/file_backed_memory``, defaulting to 0 (disabled).

    ``[libvirt]/file_backed_memory`` specifies the available capacity in MiB
    for file backed memory, at the directory configured for
    ``memory_backing_dir`` in libvirt's ``qemu.conf``. When enabled, the
    libvirt driver will report the configured value for the total memory
    capacity of the node, and will report used memory as the sum of all
    configured guest memory.

    Running Nova with file_backed_memory requires libvirt version 4.0.0 and
    qemu version 2.6.0
