Subject: Re: [PATCH V5 2/6 net-next] netdevice.h: Add zero-copy flag in
 netdevice
From: Shirley Ma <mashirle@us.ibm.com>
To: =?UTF-8?Q?Micha=C5=82_Miros=C5=82aw?= <mirqus@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
        Ben Hutchings <bhutchings@solarflare.com>,
        David Miller <davem@davemloft.net>,
        Eric Dumazet <eric.dumazet@gmail.com>, Avi Kivity <avi@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, netdev@vger.kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
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Date: Tue, 17 May 2011 15:28:38 -0700
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On Tue, 2011-05-17 at 23:48 +0200, Michał Mirosław wrote:
> 2011/5/17 Shirley Ma <mashirle@us.ibm.com>:
> > Hello Michael,
> >
> > Looks like to use a new flag requires more time/work. I am thinking
> > whether we can just use HIGHDMA flag to enable zero-copy in macvtap
> to
> > avoid the new flag for now since mavctap uses real NICs as lower
> device?
> 
> Is there any other restriction besides requiring driver to not recycle
> the skb? Are there any drivers that recycle TX skbs? 

Not more other restrictions, skb clone is OK. pskb_expand_head() looks
OK to me from code review.

Currently there is no drivers recycle TX skbs.

Thanks
Shirley

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