[PATCH v2] pcapng: allow any protocol link type for the interface block

[Dylan Schneider]

Hey Thomas,
In DPDK test cases, I agree that nothing other than Ethernet link types are currently used. However, when using DPDK Rawdev, the protocol is not usually Ethernet. In my case, I am trying to create PCAP files based on custom PCI-e traffic. The DPDK pcapng library currently hardcodes the metadata to be Ethernet, which cannot be read properly by Wireshark. Allowing the user to specify the protocol link type, the user can ensure the pcapng metadata matches the traffic data.
Dylan
________________________________
From: Thomas Monjalon <thomas at monjalon.net>
Sent: Saturday, September 27, 2025 3:28 AM
To: Dylan Schneider <schneide at qti.qualcomm.com>
Cc: dev at dpdk.org <dev at dpdk.org>; Reshma Pattan <reshma.pattan at intel.com>; Jerin Jacob <jerinj at marvell.com>; Kiran Kumar K <kirankumark at marvell.com>; Nithin Dabilpuram <ndabilpuram at marvell.com>; Zhirun Yan <yanzhirun_163 at 163.com>; Stephen Hemminger <stephen at networkplumber.org>
Subject: Re: [PATCH v2] pcapng: allow any protocol link type for the interface block

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26/09/2025 02:04, Stephen Hemminger:
> On Wed, 27 Aug 2025 16:32:15 -0600
> Schneide <schneide at qti.qualcomm.com> wrote:
>
> >
> > +* pcapng: Changed the API for adding interfaces to include a link type argument.
> > +  The link type was previously hardcoded to the ethernet link type in the API.
> > +  This argument is added to ``rte_pcapng_add_interface``.
> > +  These functions are versioned to retain binary compatibility until the next LTS release.
>
> Since link connector is now merged, and that wording might overlap and
> be confusing. Would be could to add reference to pcap-linktype.7 man
> page.

I'm not sure it overlaps.
RTE_ETH_LINK_CONNECTOR is about Ethernet cables while
pcap link type will be simply Ethernet type.

This being said, I don't understand the immediate benefit of this commit.
Why pcap link type would not be always Ethernet in DPDK case?
I think the only benefit is for future if other link types are added.
Is there something else I'm missing?


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