> -----Original Message----- > From: Olivier MATZ [mailto:olivier.matz at 6wind.com] > Sent: Wednesday, November 26, 2014 11:15 AM > To: Ananyev, Konstantin; dev at dpdk.org > Cc: Walukiewicz, Miroslaw; Liu, Jijiang; Liu, Yong; jigsaw at gmail.com; > Richardson, Bruce > Subject: Re: [PATCH v3 08/13] testpmd: rework csum forward engine > > Hi Konstantin, > > On 11/26/2014 11:10 AM, Ananyev, Konstantin wrote: > > As I can see you removed code that sets up TX_PKT_IPV4 and TX_PKT_IPV6 of > > ol_flags. > > I think that we need to keep it. > > The reason for that is: > > With FVL, to make HW TX checksum offload work, SW is responsible to provide > > to the HW information about L3 header. > > Possible values are: > > - IPv4 hdr with HW checksum calculation > > - IPV4 hdr (checksum done by SW) > > - IPV6 hdr > > - unknown > > So let say to for the packet: ETHER_HDR/IPV6_HDR/TCP_HDR/DATA > > To request HW TCP checksum offload, SW have to provide to HW information > > that it is a packet with IPV6 header > > (plus as for ixgbe: l2_hdr_len, l3_hdr_len, l4_type, l4_hdr_len). > > That's why TX_PKT_IPV4 and TX_PKT_IPV6 were introduced. > > > > Yes, it is a change in public API for HW TX offload, but I don't see any > > other way we can overcome it > > (apart from make TX function itself to parse a packet, which is obviously > > not a good choice). > > Note that existing apps working on existing HW (ixgbe/igb/em) are not > > affected. > > Though apps that supposed to be run on FVL HW too have to follow new > > convention. > > > > So I suggest we keep setting these flags in csumonly.c > > Right, I missed these flags. > It's indeed an API change, but maybe it makes sense, and setting it > is not a big cost for the application. > > So I would also need to slightly modify the API help in the following > patches: > - [04/13] mbuf: add help about TX checksum flags > - [10/13] mbuf: generic support for TCP segmentation offload > > I'll send a v4 this afternoon that integrates this change.
Ok, thanks. > > Do you know precisely when the flags PKT_TX_IPV4 and PKT_TX_IPV6 must > be set by the application? Is it only the hw checksum and tso use case? Yes, I believe it should be set only for hw checksum and tso. > If yes, I'll add it in the API help too. > > By the way (this is probably off-topic), but I'm wondering if the TX > flags should have the same values than the RX flags: > > #define PKT_TX_IPV4 PKT_RX_IPV4_HDR > #define PKT_TX_IPV6 PKT_RX_IPV6_HDR Thought about that too. >From one side, it is a bit out of our concept: separate RX and TX falgs. >From other side, it allows us to save 2 bits in the ol_flags. Don't have any strong opinion here. What do you think? > > > Apart from that , the patch looks good to me. > > And yes, we would need to change the the way we handle TX offload for > > tunnelled packets. > > Thank you very much Konstantin for your review. > > Regards, > Olivier
