[dpdk-dev] [RFC v2] doc: announce max Rx packet len field deprecation
Ajit Khaparde
ajit.khaparde at broadcom.com
Tue Nov 24 18:47:18 CET 2020
On Tue, Nov 24, 2020 at 9:36 AM Ferruh Yigit <ferruh.yigit at intel.com> wrote:
>
> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
> Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
Acked-by: Ajit Khaparde <ajit.khaparde at broadcom.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>
>
> v2:
> * ``uint32_t mtu`` moved to ``struct rte_eth_conf``
> * The "Driver is responsible from updating ``(struct
> rte_eth_dev)->data->mtu``" updated because ethdev layer also can do
> this. The intention there was both APIs should update the variable.
>
> Another open question is from Andrew, if we can remove the ``uint32_t
> max_rx_pkt_len`` completely from the ``rte_eth_dev_configure()``.
> This may force applications to have one more additional
> ``rte_eth_dev_set_mtu()`` call for device initialization, but if
> applications are OK with the default values most of times, agree that
> removing is easier solution, please comment.
> ---
> 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 96986fabd598..73e43581d615 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -88,6 +88,31 @@ Deprecation Notices
> will be limited to maximum 256 queues.
> Also compile time flag ``RTE_ETHDEV_QUEUE_STAT_CNTRS`` will be removed.
>
> +* ethdev: ``uint32_t max_rx_pkt_len`` field of ``struct rte_eth_rxmode``, will be
> + replaced by a new ``uint32_t mtu`` field of ``struct rte_eth_conf`` 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.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.
> + ``(struct rte_eth_dev)->data->mtu`` should be updated after MTU set successfully,
> + either by ``rte_eth_dev_configure()`` or ``rte_eth_dev_set_mtu()``.
> +
> + An 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 an 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``
> +
> * sched: To allow more traffic classes, flexible mapping of pipe queues to
> traffic classes, and subport level configuration of pipes and queues
> changes will be made to macros, data structures and API functions defined
> --
> 2.26.2
>
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