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

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

If builtin-net-driver option is enabled, simple vhost device will not
enable protocol feature bit. QEMU vhost net device startup will be
failed without protocol feature. Then QEMU process will be aborted when
reloading virtio net driver due to previous failure.

Signed-off-by: Marvin Liu <yong.liu@intel.com>

diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst
index 9112e7897..01adae408 100644
--- a/doc/guides/sample_app_ug/vhost.rst
+++ b/doc/guides/sample_app_ug/vhost.rst
@@ -158,6 +158,10 @@ 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**
+The builtin-net-driver option enabled very simple enqueue and dequeue function.
+This option is disabled by default.
+
 Common Issues
 -------------
 
@@ -192,3 +196,10 @@ Common Issues
   according to the NIC's property. ::
 
       make EXTRA_CFLAGS="-DMAX_QUEUES=320"
+
+* QEMU abort when builtin-net-driver option enabled
+
+  QEMU vhost net device startup will be failed without
+  VHOST_USER_F_PROTOCOL_FEATURES feature bit. Thus will cause QEMU process
+  abort when reloading virtio driver. DPDK vhost-user can be the replacement
+  of QEMU.
-- 
2.17.0