@@ -195,6 +195,9 @@ will not be set if there is no IPv6 address on the default Ethernet interface.

 Setting it here also makes it available for ``openrc`` to set ``OS_AUTH_URL``.

 ``HOST_IPV6`` is not set by default.

+For architecture specific configurations which differ from the x86 default

+here, see `arch-configuration`_.

+

 Historical Notes

 ================

@@ -749,3 +752,60 @@ overridden by setting them in the ``localrc`` section.

     ::

         TERMINATE_TIMEOUT=30

+

+

+.. _arch-configuration:

+

+Architectures

+-------------

+

+The upstream CI runs exclusively on nodes with x86 architectures, but

+OpenStack supports even more architectures. Some of them need to configure

+Devstack in a certain way.

+

+KVM on s390x (IBM z Systems)

+~~~~~~~~~~~~~~~~~~~~~~~~~~~~

+

+KVM on s390x (IBM z Systems) is supported since the *Kilo* release. For

+an all-in-one setup, these minimal settings in the ``local.conf`` file

+are needed::

+

+    [[local|localrc]]

+    ADMIN_PASSWORD=secret

+    DATABASE_PASSWORD=$ADMIN_PASSWORD

+    RABBIT_PASSWORD=$ADMIN_PASSWORD

+    SERVICE_PASSWORD=$ADMIN_PASSWORD

+

+    DOWNLOAD_DEFAULT_IMAGES=False

+    IMAGE_URLS="https://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-s390x-disk1.img"

+

+    enable_service n-sproxy

+    disable_service n-novnc

+    disable_service etcd3  # https://bugs.launchpad.net/devstack/+bug/1693192

+

+    [[post-config|$NOVA_CONF]]

+

+    [serial_console]

+    base_url=ws://$HOST_IP:6083/  # optional

+

+Reasoning:

+

+* The default image of Devstack is x86 only, so we deactivate the download

+  with ``DOWNLOAD_DEFAULT_IMAGES``. The referenced guest image

+  in the code above (``IMAGE_URLS``) serves as an example. The list of

+  possible s390x guest images is not limited to that.

+

+* This platform doesn't support a graphical console like VNC or SPICE.

+  The technical reason is the missing framebuffer on the platform. This

+  means we rely on the substitute feature *serial console* which needs the

+  proxy service ``n-sproxy``. We also disable VNC's proxy ``n-novnc`` for

+  that reason . The configuration in the ``post-config`` section is only

+  needed if you want to use the *serial console* outside of the all-in-one

+  setup.

+

+* The service ``etcd3`` needs to be disabled as long as bug report

+  https://bugs.launchpad.net/devstack/+bug/1693192 is not resolved.

+

+.. note:: To run *Tempest* against this *Devstack* all-in-one, you'll need

+   to use a guest image which is smaller than 1GB when uncompressed.

+   The example image from above is bigger than that!