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Subject: Re: [PATCH] Gigabit Ethernet driver of Topcliff PCH
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Masayuki Ohtake <masa-korg@dsn.okisemi.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>, Sam Ravnborg <sam@ravnborg.org>,
        Joe Perches <joe@perches.com>, LKML <linux-kernel@vger.kernel.org>,
        ML netdev <netdev@vger.kernel.org>,
        Greg Rose <gregory.v.rose@intel.com>, Maxime Bizon <mbizon@freebox.fr>,
        Kristoffer Glembo <kristoffer@gaisler.com>,
        Ralf Baechle <ralf@linux-mips.org>, John Linn <john.linn@xilinx.com>,
        Randy Dunlap <randy.dunlap@oracle.com>,
        "David S. Miller" <davem@davemloft.net>, MeeGo <meego-dev@meego.com>,
        "Wang, Qi" <qi.wang@intel.com>, "Wang, Yong Y" <yong.y.wang@intel.com>,
        Andrew <andrew.chih.howe.khor@intel.com>,
        Intel OTC <joel.clark@intel.com>,
        "Foster, Margie" <margie.foster@intel.com>,
        Toshiharu Okada <okada533@dsn.okisemi.com>,
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        Takahiro Shimizu <shimizu394@dsn.okisemi.com>
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Date: Fri, 03 Sep 2010 15:43:36 +0200
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Le vendredi 03 septembre 2010 à 22:32 +0900, Masayuki Ohtake a écrit :
> Hi Eric and Stephen
> 
> Thank you for your suggestion.
> 
> I tried modification of "dev->hard_header_len".
> However, there was no changed to a format of SKB received by kernel.
>   [Header:14octet] + [payload]
> 
> So, I can not a single memcpy.

Hmm, maybe you did this at the wrong place ?

Take a look at other drivers how they do this

(network stack default hard_header_len to 14, in net/ethernet/eth.c,
function ether_setup())


find drivers/net | xargs grep -n hard_header_len

Example in drivers/net/wan/hdlc.c

static void hdlc_setup_dev(struct net_device *dev)
{
        /* Re-init all variables changed by HDLC protocol drivers,
         * including ether_setup() called from hdlc_raw_eth.c.
         */
        dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
        dev->priv_flags          = IFF_WAN_HDLC;
        dev->mtu                 = HDLC_MAX_MTU;
        dev->type                = ARPHRD_RAWHDLC;
        dev->hard_header_len     = 16;
        dev->addr_len            = 0;
        dev->header_ops          = &hdlc_null_ops;
}