[dpdk-dev] [PATCH v2] doc: add note for builtin-net-driver option

[Marvin Liu <yong.liu@intel.com>]

Option builtin-net-driver is used to demonstrate how to implement
vhost-user driver based on vhost lib APIs. Unfortunately, very simple
vhost driver in vhost sample is incompatible with QEMU as protocol
feature not supported.

Signed-off-by: Marvin Liu <yong.liu@intel.com>
---
v2:
* Updated descriptions.
---
diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst
index 9112e7897..396d83211 100644
--- a/doc/guides/sample_app_ug/vhost.rst
+++ b/doc/guides/sample_app_ug/vhost.rst
@@ -158,6 +158,11 @@ when disabling VLAN strip. Such feature, which heavily depends on hardware,
 should be removed from this example to reduce confusion. Now, VLAN strip is
 enabled and cannot be disabled.
 
+**--builtin-net-driver**
+Very simple enqueue and dequeue function will be used when this option is
+given. It can demonstrate how to construct vhost-user driver with vhost lib
+APIs. It is disabled by default.
+
 Common Issues
 -------------
 
@@ -192,3 +197,8 @@ Common Issues
   according to the NIC's property. ::
 
       make EXTRA_CFLAGS="-DMAX_QUEUES=320"
+
+* Option "builtin-net-driver" is incompatible with QEMU.
+
+  QEMU vhost net device start will fail if protocol feature is not
+  negotiated. DPDK virtio-user can be the replacement of QEMU.
-- 
2.17.0