> -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > Sent: Wednesday, November 12, 2014 9:26 PM > To: Liu, Jijiang > Cc: Zhang, Helin; dev at dpdk.org; Richardson, Bruce > Subject: Re: [dpdk-dev] [PATCH v6 1/9] librte_mbuf:the rte_mbuf structure > changes > > 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 at dpdk.org] On Behalf Of Thomas Monjalon > > > 2014-10-21 14:14, Liu, Jijiang: > > > > From: Thomas Monjalon [mailto:thomas.monjalon at 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 Though I haven't investigate this too much, my opinion is that we should use packet_type in the future, and rework igb/ixgbe PMD to remove all packet types in ol_flags and use packet_type instead. Then example app can use the packet type directly. And all igb, ixgbe and i40e packet_type are consistent. Sure we might need to define all packet types in rte_ethdev.h or similar header files.
> > 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 Regards, Helin
