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[109.190.92.136]) by mx.google.com with ESMTPSA id bq6sm21667797wib.1.2014.11.12.05.26.37 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Nov 2014 05:26:38 -0800 (PST) From: Thomas Monjalon To: "Liu, Jijiang" Date: Wed, 12 Nov 2014 14:26:17 +0100 Message-ID: <2835075.ZIuhO63ZWU@xps13> Organization: 6WIND User-Agent: KMail/4.14.2 (Linux/3.17.2-1-ARCH; KDE/4.14.2; x86_64; ; ) In-Reply-To: References: <1413881168-20239-1-git-send-email-jijiang.liu@intel.com> <1710340.mrZid3JfsP@xps13> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v6 1/9] librte_mbuf:the rte_mbuf structure changes X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Nov 2014 13:16:45 -0000 Hi guys, We still have some problems with the mbuf changes introduced for VXLAN. I want to raise the packet type issue here. 2014-10-23 02:23, Zhang, Helin: > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas Monjalon > > 2014-10-21 14:14, Liu, Jijiang: > > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > > > > 2014-10-21 16:46, Jijiang Liu: > > > > > - uint16_t reserved2; /**< Unused field. Required for padding */ > > > > > + > > > > > + /** > > > > > + * Packet type, which is used to indicate ordinary L2 packet format and > > > > > + * also tunneled packet format such as IP in IP, IP in GRE, MAC in GRE > > > > > + * and MAC in UDP. > > > > > + */ > > > > > + uint16_t packet_type; > > > > > > > > Why not name it "l2_type"? > > 'packet_type' is for storing the hardware identified packet type upon different layers > of protocols (l2, l3, l4, ...). > It is quite useful for user application or middle layer software stacks, it can know > what the packet type is without checking the packet too much by software. > Actually ixgbe already has packet types (less than 10), which is transcoded into 'ol_flags'. > For i40e, the packet type can represent about 256 types of packet, 'ol_flags' does not > have enough bits for it anymore. So put the i40e packet types into mbuf would be better. > Also this field can be used for NON-Intel NICs, I think there must be the similar concepts > of other NICs. And 16 bits 'packet_type' has severl reserved bits for future and NON-Intel NICs. Thanks Helin, that's the best description of packet_type I've seen so far. It's not so clear in the commit log: http://dpdk.org/browse/dpdk/commit/?id=73b7d59cf4f6faf > > > In datasheet, this term is called packet type(s). > > > > That's exactly the point I want you really understand! > > This is a field in generic mbuf structure, so your datasheet has no value here. > > > > > Personally , I think packet type is more clear what meaning of this field is . > > > > You cannot add an API field without knowing what will be its generic meaning. > > Please think about it and describe its scope. I integrated this patch with the VXLAN patchset in the hope that you'll improve the situation afterwards. This is the answer you recently gave to Olivier: http://dpdk.org/ml/archives/dev/2014-November/007599.html " Regarding adding a packet_type in mbuf, we ever had a lot of discussions as follows: http://dpdk.org/ml/archives/dev/2014-October/007027.html http://dpdk.org/ml/archives/dev/2014-September/005240.html http://dpdk.org/ml/archives/dev/2014-September/005241.html http://dpdk.org/ml/archives/dev/2014-September/005274.html " To sum up the situation: - We don't know what are the possible values of packet_type - It's only filled by i40e, while other drivers use ol_flags - There is no special value "unknown" which should be set by drivers not supporting this feature. - Its only usage is to print a decimal value in app/test-pmd/rxonly.c It's now clear that nobody cares about this part of the API. So I'm going to remove packet_type from mbuf. I don't want to keep something that we don't know how to use, that is not consistent across drivers, and that overlap another API part (ol_flags). -- Thomas