Re: [dpdk-dev] [RFC] ethdev: add min/max MTU to device info

[Shahaf Shuler <shahafs@mellanox.com>]

Wednesday, September 5, 2018 7:42 PM, Stephen Hemminger:
> Subject: [dpdk-dev] [RFC] ethdev: add min/max MTU to device info
> 
> This addresses the usability issue raised by OVS at DPDK Userspace summit.
> It adds general min/max mtu into device info. For compatiablity, and to save
> space, it fits in a hole in existing structure.
> 
> The initial version sets max mtu to normal Ethernet, it is up to PMD to set
> larger value if it supports Jumbo frames.
> 
> Fixing the drivers to use this is trivial and can be done by 18.11.
> Already have some of the patches done.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Makes sense.
Acked-by: Shahaf Shuler <shahafs@mellanox.com>

> ---
>  lib/librte_ethdev/rte_ethdev.c | 7 +++++++  lib/librte_ethdev/rte_ethdev.h
> | 2 ++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index 4c320250589a..df0c7536a7c4 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -2408,6 +2408,8 @@ rte_eth_dev_info_get(uint16_t port_id, struct
> rte_eth_dev_info *dev_info)
>  	dev_info->rx_desc_lim = lim;
>  	dev_info->tx_desc_lim = lim;
>  	dev_info->device = dev->device;
> +	dev_info->min_mtu = ETHER_MIN_MTU;
> +	dev_info->max_mtu = ETHER_MTU;
> 
>  	RTE_FUNC_PTR_OR_RET(*dev->dev_ops->dev_infos_get);
>  	(*dev->dev_ops->dev_infos_get)(dev, dev_info); @@ -2471,12
> +2473,17 @@ int  rte_eth_dev_set_mtu(uint16_t port_id, uint16_t mtu)  {
>  	int ret;
> +	struct rte_eth_dev_info dev_info;
>  	struct rte_eth_dev *dev;
> 
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>  	dev = &rte_eth_devices[port_id];
>  	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->mtu_set, -
> ENOTSUP);
> 
> +	rte_eth_dev_info_get(port_id, &dev_info);
> +	if (mtu < dev_info.min_mtu || mtu > dev_info.max_mtu)
> +		return -EINVAL;
> +
>  	ret = (*dev->dev_ops->mtu_set)(dev, mtu);
>  	if (!ret)
>  		dev->data->mtu = mtu;
> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> index 7070e9ab408f..5171a9083288 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -1015,6 +1015,8 @@ struct rte_eth_dev_info {
>  	const char *driver_name; /**< Device Driver name. */
>  	unsigned int if_index; /**< Index to bound host interface, or 0 if
> none.
>  		Use if_indextoname() to translate into an interface name. */
> +	uint16_t min_mtu;	/**< Minimum MTU allowed */
> +	uint16_t max_mtu;	/**< Maximum MTU allowed */
>  	const uint32_t *dev_flags; /**< Device flags */
>  	uint32_t min_rx_bufsize; /**< Minimum size of RX buffer. */
>  	uint32_t max_rx_pktlen; /**< Maximum configurable length of RX
> pkt. */
> --
> 2.17.1