---
prelude: |
    The 26.0.0 release includes many new features and bug fixes. Please be
    sure to read the upgrade section which describes the required actions to
    upgrade your cloud from 25.0.0 (Yoga) to 26.0.0 (Zed).

    There are a few major changes worth mentioning. This is not an exhaustive
    list:

    - The latest Compute API microversion supported for Zed is `v2.93`__.

      .. __: https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#maximum-in-zed

    - `Virtual IOMMU devices`__  can now be created and attached to an instance
      when running on a x86 host
      and using the libvirt driver.

      .. __: https://docs.openstack.org/nova/latest/admin/pci-passthrough.html#virtual-iommu-support

    - Improved behavior for Windows guest by adding by default following
      `Hyper-V enlightments`__ on all libvirt guests : `vpindex`, `runtime`,
      `synic`, `reset`, `frequencies`, `reenlightenment`, `tlbflush`, `ipi` and
      `evmc`.

      .. __: https://libvirt.org/formatdomain.html#hypervisor-features

    - All lifecycle actions are now fully supported for
      `instances with vDPA ports`__, including vDPA hot-plug live migration,
      suspend and attach/detach.

      .. __: https://docs.openstack.org/nova/latest/admin/vdpa.html

    - Volume-backed instances (instances with root disk attached as a volume)
      can now be rebuilt by specifying a 2.93 microversion instead of returning
      a HTTP400 exception.

    - The `unshelve` instance API action now provides a new `host` parameter
      with 2.91 microversion (for only admins).

    - With microversion 2.92, you can only import a public key and not generate
      a keypair. You can also use an extended name pattern.

    - The default system scope is removed from all APIs hence finishing to
      implement `phase #1 of new RBAC guidelines`__ that are opt-in.

      .. __: https://governance.openstack.org/tc/goals/selected/consistent-and-secure-rbac.html#phase-1