NEWS: Deprecate running user-space with OOT Kernel module.

It is some time now since the OOT kernel module was removed. It is yet
longer since it was deprecated. And it is no longer present in any
supported versions.

However, running user-space with the OOT kernel module, from unsupported
releases, is still supported.

This notice deprecates that support as of the v3.7 release.
With the intention to remove it in the v3.8 release.

As discussed at OVS+OVN Conference 2025.

Acked-by: Eelco Chaudron <[email protected]>
Signed-off-by: Simon Horman <[email protected]>

Author: Simon Horman

NEWS

@@ -18,6 +18,13 @@ Post-v3.6.0
        to modify the database data through this transaction.
    - Windows Support
      * Support for compiling for and running on Windows has been deprecated.
+   - Deprecation of support for running OVS user-space with OOT kernel module
+     * The OOT kernel module refers to the kernel module that was
+       previously distributed as part of OVS - out of tree (OOT) from the
+       perspective of the upstream Kernel tree.
+     * The OOT kernel module: was deprecated in v2.15; was last present in
+       the v2.17 release; and is no longer present in any supported release
+       since v2.17 went EOL when v3.5 was released.
 
 
 v3.6.0 - 18 Aug 2025

lib/dpif-netlink-rtnl.c

@@ -542,8 +542,8 @@ dpif_netlink_rtnl_port_destroy(const char *name, const char *type)
  *
  * See ovs_tunnels_out_of_tree
  */
-bool
-dpif_netlink_rtnl_probe_oot_tunnels(void)
+static bool
+dpif_netlink_rtnl_probe_oot_tunnels__(void)
 {
     char namebuf[NETDEV_VPORT_NAME_BUFSIZE];
     struct netdev *netdev = NULL;
@@ -624,3 +624,17 @@ dpif_netlink_rtnl_probe_oot_tunnels(void)
 
     return out_of_tree;
 }
+
+bool
+dpif_netlink_rtnl_probe_oot_tunnels(void)
+{
+    bool out_of_tree = dpif_netlink_rtnl_probe_oot_tunnels__();
+
+    if (out_of_tree) {
+        VLOG_WARN_ONCE("Use of the OOT Kernel datapath module is deprecated. "
+                       "Please use the module provided by the upstream "
+                       "Kernel instead.");
+    }
+
+    return out_of_tree;
+}