Re: [dpdk-dev] [PATCH] net/i40e: fix max frame size checking

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zhang, Qi Z
> Sent: Thursday, July 26, 2018 8:14 PM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Wu, Yanglong
> <yanglong.wu@intel.com>; dev@dpdk.org
> Cc: Bie, Tiwei <tiwei.bie@intel.com>; Yao, Lei A <lei.a.yao@intel.com>; Wu,
> Yanglong <yanglong.wu@intel.com>
> Subject: Re: [dpdk-dev] [PATCH] net/i40e: fix max frame size checking
> 
> 
> 
> > -----Original Message-----
> > From: Ananyev, Konstantin
> > Sent: Thursday, July 26, 2018 5:17 PM
> > To: Wu, Yanglong <yanglong.wu@intel.com>; dev@dpdk.org
> > Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; Bie, Tiwei
> > <tiwei.bie@intel.com>; Yao, Lei A <lei.a.yao@intel.com>; Wu, Yanglong
> > <yanglong.wu@intel.com>
> > Subject: RE: [dpdk-dev] [PATCH] net/i40e: fix max frame size checking
> >
> >
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Yanglong Wu
> > > Sent: Thursday, July 26, 2018 7:46 AM
> > > To: dev@dpdk.org
> > > Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; Bie, Tiwei
> > > <tiwei.bie@intel.com>; Yao, Lei A <lei.a.yao@intel.com>; Wu,
> > > Yanglong <yanglong.wu@intel.com>
> > > Subject: [dpdk-dev] [PATCH] net/i40e: fix max frame size checking
> > >
> > > No need to check max frame size in TX, the checking should be done
> > > in up layer protocal. This checking will lead to fail for TSO or
> > > other application cases.
> >
> > Not sure why is that?
> > i40e doesn't support single packet bigger then 9.5KB (or so), as I remember.
> > For TSO the limit is 256KB - yes, it is bibber, but still there is a limit.
> 
> I think we can't support more than 8 segment for TSO, right? so if the limit is
> 256KB, seems it is a redundant.

I mean buffer size limit is 16kb according to datasheet.

> 
> > Might be we need to change that check, but I think we still need to keep it.
> > Konstantin
> 
> >
> > >
> > > Fixes: bfeed0262b0c ("net/i40e: check illegal packets")
> > >
> > > Signed-off-by: Yanglong Wu <yanglong.wu@intel.com>
> > > ---
> > >  drivers/net/i40e/i40e_rxtx.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/i40e/i40e_rxtx.c
> > > b/drivers/net/i40e/i40e_rxtx.c index 3be87fe6a..baad433a7 100644
> > > --- a/drivers/net/i40e/i40e_rxtx.c
> > > +++ b/drivers/net/i40e/i40e_rxtx.c
> > > @@ -1459,8 +1459,7 @@ i40e_prep_pkts(__rte_unused void *tx_queue,
> > struct rte_mbuf **tx_pkts,
> > >  		}
> > >
> > >  		/* check the size of packet */
> > > -		if (m->pkt_len > I40E_FRAME_SIZE_MAX ||
> > > -		    m->pkt_len < I40E_TX_MIN_PKT_LEN) {
> > > +		if (m->pkt_len < I40E_TX_MIN_PKT_LEN) {
> > >  			rte_errno = -EINVAL;
> > >  			return i;
> > >  		}
> > > --
> > > 2.11.0