> -----Original Message----- > From: Ananyev, Konstantin > Sent: Tuesday, February 3, 2015 1:20 AM > To: Olivier MATZ; Zhang, Helin; dev at dpdk.org > Subject: RE: [dpdk-dev] [PATCH 00/17] unified packet type > > Hi Olivier, > > > -----Original Message----- > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Olivier MATZ > > Sent: Monday, February 02, 2015 11:38 AM > > To: Zhang, Helin; dev at dpdk.org > > Subject: Re: [dpdk-dev] [PATCH 00/17] unified packet type > > > > Hi Helin, > > > > On 02/02/2015 03:44 AM, Zhang, Helin wrote: > > >>>> Let's take a simple example. Imagine a hardware-1 that is able to > > >>>> recognize an IP packet by checking the ethertype and that the IP > > >>>> version is set to 4. > > >>>> Another hardware-2 recognize an IP packet by checking the > > >>>> ethertype, the IP version and that the IP length is correct compared to > m_len(m). > > >>>> > > >>>> For the same packet, both hardwares will return > > >>>> RTE_PTYPE_L3_IPV4, but they don't do the same checks on the > > >>>> packet. As I want my application behave exactly the same whatever > > >>>> the hardware, I need to know what checks are done in hardware, so > > >>>> I can decide what checks must be done in my application. > > >>>> > > >>>> Example of definition: RTE_PTYPE_L3_IPV4 means that ethertype is > > >>>> 0x0800 and IP.version is 4. > > >>>> > > >>>> It means that I can skip these 2 tests in my application if I > > >>>> have this packet_type, but all other checks must be done in > > >>>> software (ip length, flags, checksum, ...) > > >>>> > > >>>> For each packet type, we need a definition like above, and we > > >>>> must check that all drivers setting a packet type behave like > > >>>> described. > > > Hmm, I think the packet_type may need to be renamed to else, like > offload_packet_type. > > > It is just for hardware reported packet type information. It is not > > > for all information of a packet. > > > As different hardware may have different capability, it cannot > > > report the same in mbuf among different hardware for the same packet. > > > With your question, I think the hardware capability flags may be > > > needed. Applications can query the packet type capabilities on each > > > port, then it knows what type of packet type information can be reported > > > by > the corresponding hardware. > > > What do you think? And are they any better ideas from you? > > > > I'm not sure renaming the field would change something here. > > > > The high-level question is: how a software can take advantage of this > > information given by the hardware? If the same packet_type does not > > have the same meaning depending on the hardware, it's not worth having > > this info. > > > > I think the API should describe for each packet type what can be > > expected by the application. Here is an example. When a driver sets > > the > > RTE_PTYPE_L3_IPV4 type, it means that: > > > > - the layer 3 is identified as IP by underlying layer (ex: ethertype=IP > > if layer 2 is ethernet) > > - the IP version field is 4 > > - there is no IP options (i.e the size of header is 20) > > Yes, I suppose that's what supported HW can guarantee when > RTE_PTYPE_L3_IPV4 is set. > > > - the checksum field has been verified by hw, and if wrong, the > > flag PKT_RX_IP_CKSUM_BAD is set > > Hmm, why is that? > As I remember on many devices it is configurable by SW should HW do RX > checksum offload or not. > From DPDK point of view there is hw_ip_checksum field in rte_eth_rxmode. > So it is a possible situation, when at RX HW does packet type determination, > but doesn't make L3/L4 checksum calculation. > > I suppose for checksum(s) it should be a separate flags (in ol_flags) with 3 > possible values: > CKSUM_UNKNOWN, CKSUM_BAD, CKSUM_OK. > > Konstantin
I think packet type and checksum are totally different things in DPDK, though they might have dependencies in hardware. Checksum good/bad is still indicated in ol_flags. Packet type is nothing about checksum. Regards, Helin > > > > > If the hardware is not able to give all this information, there are > > 2 solutions: > > - do the remaining tests in the driver > > - or set l3 pkt_type to unknown > > > > All other conditions that are not described in the API should be > > checked by the applition if it needs the information (ex: check that > > IP dest address is legal, that ip->len is >= 20, ...). > > > > > > If we are able to describe this for all packet types, it would really > > help application to take advantage of these packet types. > > > > Regards, > > Olivier
