[PATCH] content: explicitly document the VLAN filtering as best-effort

[Tiwei Bie <tiwei.bie@intel.com>]

Similar to the MAC address based filtering, the VLAN filtering
is also best-effort in implementations, but it's not quite clear
in the spec. So document this behaviour explicitly to reflect
the way implementations behave.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/47
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---
v1:
- Add "Fixes:" tag;

RFC link:
https://lists.oasis-open.org/archives/virtio-dev/201907/msg00035.html

 content.tex | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/content.tex b/content.tex
index 8f0498e..783322b 100644
--- a/content.tex
+++ b/content.tex
@@ -3530,6 +3530,11 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
 If the driver negotiates the VIRTION_NET_F_CTRL_VLAN feature, it
 can control a VLAN filter table in the device.
 
+\begin{note}
+Similar to the MAC address based filtering, the VLAN filtering
+is also best-effort: unwanted packets could still arrive.
+\end{note}
+
 \begin{lstlisting}
 #define VIRTIO_NET_CTRL_VLAN       2
  #define VIRTIO_NET_CTRL_VLAN_ADD             0
-- 
2.17.1