doc/userguide: af-packet upgrade notes

Add note about increased block size and how to change it back to old
defaults if needed.

Ticket: #7458
(cherry picked from commit c6d18fc871ed5466f519a4109d81ca193c92fc7e)

diff --git a/doc/userguide/upgrade.rst b/doc/userguide/upgrade.rst
index 2cc195fd260beb96371cb3b89622bfea5c2e65b4..a78dd730c764062e7d2fa9092dfda5e09dda294e 100644 (file)
--- a/doc/userguide/upgrade.rst
+++ b/doc/userguide/upgrade.rst
@@ -34,6 +34,17 @@ also check all the new features that have been added but are not covered by
 this guide. Those features are either not enabled by default or require
 dedicated new configuration.
 
+Upgrading to 7.0.9
+------------------
+- The AF_PACKET default block size for both TPACKET_V2 and TPACKET_V3
+  has been increased from 32k to 128k. This is to allow for full size
+  defragmented packets. For TPACKET_V3 the existing ``block-size``
+  parameter can be used to change this back to the old default of
+  32768 if needed. For TPACKET_V2 a new configuration parameter has
+  been added, ``v2-block-size`` which can be used to tune this value
+  for TPACKET_V2. Due to the increased block size, memory usage has
+  been increased, but should not be an issue in most cases.
+
 Upgrading to 7.0.8
 ------------------
 - Unknown requirements in the ``requires`` keyword will now be treated