X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=doc%2Fguides%2Fcontributing%2Fdesign.rst;h=5fe7f63942d598ad1e615a382056695c99cbfb06;hb=47909357a0697fe9aaf4f0f27939f4edcdbb5e22;hp=d3dd694b65df0b4846686414c1d94c92414b55e6;hpb=218c4e68c1d9bd4a9281bc1dc4d0ab89859083bf;p=dpdk.git

diff --git a/doc/guides/contributing/design.rst b/doc/guides/contributing/design.rst
index d3dd694b65..5fe7f63942 100644
--- a/doc/guides/contributing/design.rst
+++ b/doc/guides/contributing/design.rst
@@ -57,6 +57,22 @@ The following config options can be used:
 * ``CONFIG_RTE_EXEC_ENV`` is a string that contains the name of the executive environment.
 * ``CONFIG_RTE_EXEC_ENV_FREEBSD`` or ``CONFIG_RTE_EXEC_ENV_LINUX`` are defined only if we are building for this execution environment.
 
+Mbuf features
+-------------
+
+The ``rte_mbuf`` structure must be kept small (128 bytes).
+
+In order to add new features without wasting buffer space for unused features,
+some fields and flags can be registered dynamically in a shared area.
+The "dynamic" mbuf area is the default choice for the new features.
+
+The "dynamic" area is eating the remaining space in mbuf,
+and some existing "static" fields may need to become "dynamic".
+
+Adding a new static field or flag must be an exception matching many criteria
+like (non exhaustive): wide usage, performance, size.
+
+
 Library Statistics
 ------------------