From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailfilter02.viettel.com.vn (mailfilter02.viettel.com.vn [125.235.240.54]) by dpdk.org (Postfix) with ESMTP id 98AD74C79 for ; Fri, 23 Feb 2018 04:13:59 +0100 (CET) X-IronPort-AV: E=Sophos;i="5.47,381,1515430800"; d="scan'208,217";a="74074250" Received: from 125.235.240.44.adsl.viettel.vn (HELO mta1.viettel.com.vn) ([125.235.240.44]) by mailfilter02.viettel.com.vn with ESMTP; 23 Feb 2018 10:13:57 +0700 Received: from localhost (localhost [127.0.0.1]) by mta1.viettel.com.vn (Postfix) with ESMTP id 148D360D121; Fri, 23 Feb 2018 10:13:46 +0700 (ICT) Received: from mta1.viettel.com.vn ([127.0.0.1]) by localhost (mta1.viettel.com.vn [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id LIIvMQzxI90T; Fri, 23 Feb 2018 10:13:46 +0700 (ICT) Received: from localhost (localhost [127.0.0.1]) by mta1.viettel.com.vn (Postfix) with ESMTP id E5CCE60D11C; Fri, 23 Feb 2018 10:13:45 +0700 (ICT) X-Virus-Scanned: amavisd-new at Received: from mta1.viettel.com.vn ([127.0.0.1]) by localhost (mta1.viettel.com.vn [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id lQD_JlOYv9LC; Fri, 23 Feb 2018 10:13:45 +0700 (ICT) Received: from ANMLONGTB5 (unknown [27.68.241.28]) by mta1.viettel.com.vn (Postfix) with ESMTPSA id B672E60D110; Fri, 23 Feb 2018 10:13:45 +0700 (ICT) To: Cc: Message-ID: <000f01d3ac54$dcd2cff0$96786fd0$@viettel.com.vn> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 16.0 Thread-Index: AdOsU6hj8hkoz6UMS2SG7eIGnwSa5g== Content-Language: en-us MilterAction: FORWARD Date: Fri, 23 Feb 2018 10:13:45 +0700 (ICT) From: longtb5@viettel.com.vn Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: [dpdk-dev] Suggestions on how to customize the metadata fields of each packet X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Feb 2018 03:14:01 -0000 Hi, First, I think your question should be sent to the user mailing list, not the dev mailing list. > I have seen that each packet has a headroom memory space (128 bytes long) > where RSS hashing and other metadata provided by the NIC is stored. If I'm not mistaken, the headroom is not where metadata provided by the NIC are stored. Those metadata are stored in the rte_mbuf struct, which is also 128 bytes long. The headroom area is located AFTER the end of rte_mbuf (at offset 128). By default the headroom area is also 128 byte long, so the actual packet data is stored at offset 256. You can store whatever you want in this headroom area. However those information are lost as soon as the packet leaves DPDK (the NIC will start sending at offset 256). -BL.