From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?iso-8859-1?Q?N=E9lio?= Laranjeiro <nelio.laranjeiro@6wind.com>
Subject: Re: [PATCH v5 4/4] net/mlx5: enforce Tx num of segments
	limitation
Date: Fri, 15 Sep 2017 10:11:27 +0200
Message-ID: <20170915081127.GC2160@autoinstall.dev.6wind.com>
References: <bf55957ce3c8dc7d749ab1bb964f96bf54b31723.1505299539.git.shahafs@mellanox.com>
 <5046c30c96938a590412ce03dcad1434824cd952.1505385989.git.shahafs@mellanox.com>
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To: Shahaf Shuler <shahafs@mellanox.com>
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On Thu, Sep 14, 2017 at 01:50:39PM +0300, Shahaf Shuler wrote:
> Mellanox NICs has a limitation on the number of mbuf segments a multi
> segment mbuf can have. The max number depends on the Tx offloads requested.
> 
> The current code not enforce such limitation, which might cause
> malformed work requests to be written to the device.
> 
> This commit adds verification for the number of mbuf segments posted
> to the device. In case of overflow the packet will not be sent.
> 
> In addition update the nic documentation with the limitation.
> Considering device limitation is 63 data segments in a work request, the
> maximum number of segment in mbuf was calculated taking TSO as the worst
> case:
> 
> max_nb_segs = 63 - (control_segment + ethernet segment +
> 		    TSO headers inline + inline segment +
> 		    extra inline to align to cacheline)
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>

-- 
Nélio Laranjeiro
6WIND