[dpdk-dev] [PATCH] net/i40e: consider QinQ when setting MTU

Lu, Wenzhuo wenzhuo.lu at intel.com
Tue May 2 03:25:31 CEST 2017


Hi Ferruh,


> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Friday, April 28, 2017 8:38 PM
> To: Wu, Jingjing; Lu, Wenzhuo; dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] net/i40e: consider QinQ when setting MTU
> 
> On 4/28/2017 9:27 AM, Wu, Jingjing wrote:
> >
> >
> >> -----Original Message-----
> >> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ferruh Yigit
> >> Sent: Friday, April 28, 2017 1:55 PM
> >> To: Lu, Wenzhuo <wenzhuo.lu at intel.com>; dev at dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH] net/i40e: consider QinQ when setting
> >> MTU
> >>
> >> On 4/28/2017 2:55 AM, Wenzhuo Lu wrote:
> >>> When counting max packet length from MTU, count VLAN tag length
> >>> twice for QinQ packets.
> >>>
> >>> Signed-off-by: Wenzhuo Lu <wenzhuo.lu at intel.com>
> >>> ---
> >>>  drivers/net/i40e/i40e_ethdev.c    | 2 +-
> >>>  drivers/net/i40e/i40e_ethdev_vf.c | 2 +-
> >>>  2 files changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/net/i40e/i40e_ethdev.c
> >>> b/drivers/net/i40e/i40e_ethdev.c index 3fa25dc..74041ae 100644
> >>> --- a/drivers/net/i40e/i40e_ethdev.c
> >>> +++ b/drivers/net/i40e/i40e_ethdev.c
> >>> @@ -10593,7 +10593,7 @@ static void
> i40e_set_default_mac_addr(struct
> >> rte_eth_dev *dev,
> >>>  	struct i40e_pf *pf = I40E_DEV_PRIVATE_TO_PF(dev->data-
> >>> dev_private);
> >>>  	struct rte_eth_dev_data *dev_data = pf->dev_data;
> >>>  	uint32_t frame_size = mtu + ETHER_HDR_LEN
> >>> -			      + ETHER_CRC_LEN + I40E_VLAN_TAG_SIZE;
> >>> +			      + ETHER_CRC_LEN + I40E_VLAN_TAG_SIZE * 2;
> >>
> >> Hi Wenzhuo,
> >>
> >> Shouldn't we check if QinQ enabled before taking size account?
> >
> > Hi, Ferruh
> >
> > Checking QinQ enabled here makes no sense, because we don't know If
> > the packets is carry single vlan or double vlan.
> 
> What do you think commenting code to say "I40E_VLAN_TAG_SIZE * 2" is for
> QinQ?
> 
> It is not obvious and in the feature somebody not thinking about QinQ use
> case may miss this, and do something wrong, even can fix this J
Thanks for your suggestion. I'll send a V2 to add the comments.

> 
> >
> > Acked-by: Jingjing Wu <jingjing.wu at intel.com>
> >



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