[dpdk-dev] [PATCH v6 4/8] ethdev: add GTP items to support flow API

[Wu, Jingjing]

> -----Original Message-----
> From: Sean Harte [mailto:seanbh at gmail.com]
> Sent: Tuesday, October 3, 2017 4:57 PM
> To: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
> Cc: Xing, Beilei <beilei.xing at intel.com>; Wu, Jingjing <jingjing.wu at intel.com>; Chilikin,
> Andrey <andrey.chilikin at intel.com>; dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v6 4/8] ethdev: add GTP items to support flow API
> 
> On 2 October 2017 at 13:27, Adrien Mazarguil <adrien.mazarguil at 6wind.com> wrote:
> > On Fri, Sep 29, 2017 at 10:29:55AM +0100, Sean Harte wrote:
> >> On 29 September 2017 at 09:54, Xing, Beilei <beilei.xing at intel.com> wrote:
> > <snip>
> >> >> >  /**
> >> >> > + * RTE_FLOW_ITEM_TYPE_GTP.
> >> >> > + *
> >> >> > + * Matches a GTPv1 header.
> >> >> > + */
> >> >> > +struct rte_flow_item_gtp {
> >> >> > +       /**
> >> >> > +        * Version (3b), protocol type (1b), reserved (1b),
> >> >> > +        * Extension header flag (1b),
> >> >> > +        * Sequence number flag (1b),
> >> >> > +        * N-PDU number flag (1b).
> >> >> > +        */
> >> >> > +       uint8_t v_pt_rsv_flags;
> >> >> > +       uint8_t msg_type; /**< Message type. */
> >> >> > +       rte_be16_t msg_len; /**< Message length. */
> >> >> > +       rte_be32_t teid; /**< Tunnel endpoint identifier. */ };
> >> >>
> >> >> In future, you might add support for GTPv2 (which is used since LTE).
> >> >> Maybe this structure should have v1 in its name to avoid confusion?
> >> >
> >> > I considered it before. But I think we can modify it when we support GTPv2 in future,
> and keep concise 'GTP' currently:)  since I have described it matches v1 header.
> >> >
> >>
> >> You could rename v_pt_rsv_flags to version_flags to avoid some future
> >> code changes to support GTPv2. There's still the issue that not all
> >> GTPv2 messages have a TEID though.
> >
> > Although they have the same size, the header of these two protocols
> > obviously differs. My suggestion would be to go with a separate GTPv2
> > pattern item using its own dedicated structure instead.
> >
> > --
> > Adrien Mazarguil
> > 6WIND
> 
> The 1st four bytes are the same (flags in first byte have different
> meanings, but the bits indicating the version are in the same
> location). After that, different fields in each version are optional,
> and the headers have variable size. A single structure could be used
> if the first field is renamed to something like "version_flags", and
> then check that the teid field in item->mask is not set if
> ((version_flags >> 5 == 2) && ((version_flags >> 4) & 1) == 1). If
> there's going to be two structures, it would be good to put v1 and v2
> in the names, in my opinion.

I think the name GTP is OK for now. Due to v1 and v2 are different, why not rename them
when the v2 supporting are introduced?