[PATCH v3 4/4] doc/prog_guide: add reference to virtio-user from KNI doc

[Bruce Richardson <bruce.richardson@intel.com>]

To help encourage use of virtio-user in place of KNI, put a reference to
the relevant howto section at the top of the KNI doc.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 doc/guides/prog_guide/kernel_nic_interface.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst
index 5248f9622b..e021cc69b6 100644
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -6,6 +6,12 @@
 Kernel NIC Interface
 ====================
 
+.. note::
+
+   For an alternative to KNI, that does not require any out-of-tree Linux kernel modules,
+   or a custom library, see :ref:`virtio_user_as_exception_path`.
+
+
 The DPDK Kernel NIC Interface (KNI) allows userspace applications access to the Linux* control plane.
 
 The benefits of using the DPDK KNI are:
-- 
2.34.1