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Date: Mon, 12 May 2014 10:13:16 -0700
From: Stephen Hemminger <stephen@networkplumber.org>
To: Olivier MATZ <olivier.matz@6wind.com>
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Subject: Re: [dpdk-dev] [PATCH RFC 06/11] mbuf: replace data pointer by an
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On Mon, 12 May 2014 18:13:26 +0200
Olivier MATZ <olivier.matz@6wind.com> wrote:

> Hi Stephen,
> 
> On 05/12/2014 05:59 PM, Stephen Hemminger wrote:
> > There is one case which this case might make problematic.
> > Right now it is possible to clone an mbuf and in the cloned mbuf
> > use the associated data buffer as private meta data store.
> > This is convenient (like skb->cb in Linux) and avoids addtional
> > allocation.
> 
> I don't get your point. Why using rte_pktmbuf_mtod(m, char *)
> wouldn't work in your case?

In cloned mbuf
rte_pktmbuf_mtod(m, char *) points to the original data.
RTE_MBUF_TO_BADDR(m) points to buffer in the mbuf which we
use for metadata (timestamp).