[dpdk-dev] [RFC] doc: announce max Rx packet len field deprecation

Ferruh Yigit ferruh.yigit at intel.com
Tue Oct 20 14:03:05 CEST 2020


Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
---
Cc: Thomas Monjalon <thomas at monjalon.net>
Cc: Andrew Rybchenko <arybchenko at solarflare.com>
Cc: Konstantin Ananyev <konstantin.ananyev at intel.com>
Cc: Matan Azrad <matan at nvidia.com>
Cc: Olivier Matz <olivier.matz at 6wind.com>
Cc: Jerin Jacob <jerinj at marvell.com>
---
 doc/guides/rel_notes/deprecation.rst | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 8ceb385141..d4a31392d3 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -149,6 +149,31 @@ Deprecation Notices
   will be limited to maximum 256 queues.
   Also compile time flag ``RTE_ETHDEV_QUEUE_STAT_CNTRS`` will be removed.
 
+* ethdev: In ``struct rte_eth_rxmode``, ``uint32_t max_rx_pkt_len`` will be
+  replaced by a new ``uint32_t mtu`` in v21.11.
+  The new ``mtu`` field will be used to configure the initial device MTU via
+  ``rte_eth_dev_configure()`` API.
+  Later MTU can be changed by ``rte_eth_dev_set_mtu()`` API as done now.
+  The existing ``(struct rte_eth_dev)->data->mtu`` variable will be used to store
+  the configured ``mtu`` value,
+  and this new ``(struct rte_eth_dev)->data->dev_conf.rxmode.mtu`` variable will
+  be used to store the user configuration request.
+  Unlike ``max_rx_pkt_len``, which was valid only when ``JUMBO_FRAME`` enabled,
+  ``mtu`` field will be always valid.
+  When ``mtu`` config is not provided by the application, default ``RTE_ETHER_MTU``
+  value will be used.
+  Driver is responsible from updating ``(struct rte_eth_dev)->data->mtu`` after MTU
+  set successfully, either by ``rte_eth_dev_configure()`` or ``rte_eth_dev_set_mtu()``.
+
+  Application may need to configure device for a specific Rx packet size, like for
+  cases ``DEV_RX_OFFLOAD_SCATTER`` is not supported and device received packet size
+  can't be bigger than Rx buffer size.
+  To cover these cases application needs to know the device packet overhead to be
+  able to calculate the ``mtu`` corresponding to a Rx buffer size, for this
+  ``(struct rte_eth_dev_info).max_rx_pktlen`` will be kept,
+  the device packet overhead can be calculated as:
+  ``(struct rte_eth_dev_info).max_rx_pktlen - (struct rte_eth_dev_info).max_mtu``
+
 * cryptodev: support for using IV with all sizes is added, J0 still can
   be used but only when IV length in following structs ``rte_crypto_auth_xform``,
   ``rte_crypto_aead_xform`` is set to zero. When IV length is greater or equal
-- 
2.26.2



More information about the dev mailing list