Re: [dpdk-dev] [PATCH v4 1/2] ethdev: add new ext hdr for gtp psc

[Raslan Darawsheh <rasland@nvidia.com>]

Hi Olivier,

> -----Original Message-----
> From: Olivier Matz <olivier.matz@6wind.com>
> Sent: Thursday, April 8, 2021 3:30 PM
> To: Raslan Darawsheh <rasland@nvidia.com>
> Cc: dev@dpdk.org; ferruh.yigit@intel.com; Ori Kam <orika@nvidia.com>;
> andrew.rybchenko@oktetlabs.ru; ivan.malov@oktetlabs.ru;
> ying.a.wang@intel.com; Slava Ovsiienko <viacheslavo@nvidia.com>; Shiri
> Kuzin <shirik@nvidia.com>
> Subject: Re: [PATCH v4 1/2] ethdev: add new ext hdr for gtp psc
> 
> Hi Raslan,
> 
> On Sun, Apr 04, 2021 at 10:45:51AM +0300, Raslan Darawsheh wrote:
> > Define new rte header for gtp PDU session container
> > based on RFC 38415-g30
> 
> Do you have a link to this RFC?
Yes sure,
https://www.3gpp.org/ftp/Specs/archive/38_series/38.415/38415-g30.zip

> 
> > Signed-off-by: Raslan Darawsheh <rasland@nvidia.com>
> > ---
> >  lib/librte_net/rte_gtp.h | 34 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 34 insertions(+)
> >
> > diff --git a/lib/librte_net/rte_gtp.h b/lib/librte_net/rte_gtp.h
> > index 6a6f9b238d..088b0b5a53 100644
> > --- a/lib/librte_net/rte_gtp.h
> > +++ b/lib/librte_net/rte_gtp.h
> > @@ -61,6 +61,40 @@ struct rte_gtp_hdr_ext_word {
> >  	uint8_t next_ext;     /**< Next Extension Header Type. */
> >  }  __rte_packed;
> >
> > +/**
> > + * Optional extension for GTP with next_ext set to 0x85
> > + * defined based on RFC 38415-g30.
> > + */
> > +__extension__
> > +struct rte_gtp_psc_hdr {
> > +	uint8_t ext_hdr_len; /**< PDU ext hdr len in multiples of 4 bytes */
> > +	uint8_t type:4; /**< PDU type */
> > +	uint8_t qmp:1; /**< Qos Monitoring Packet */
> > +	union {
> > +		struct {
> > +			uint8_t snp:1; /**< Sequence number presence */
> > +			uint8_t spare_dl1:2; /**< spare down link bits */
> > +		};
> > +		struct {
> > +			uint8_t dl_delay_ind:1; /**< dl delay result presence
> */
> > +			uint8_t ul_delay_ind:1; /**< ul delay result presence
> */
> > +			uint8_t snp_ul1:1; /**< Sequence number presence
> ul */
> > +		};
> > +	};
> > +	union {
> > +		struct {
> > +			uint8_t ppp:1; /**< Paging policy presence */
> > +			uint8_t rqi:1; /**< Reflective Qos Indicator */
> > +		};
> > +		struct {
> > +			uint8_t n_delay_ind:1; /**< N3/N9 delay result
> presence */
> > +			uint8_t spare_ul2:1; /**< spare up link bits */
> > +		};
> > +	};
> > +	uint8_t qfi:6; /**< Qos Flow Identifier */
> > +	uint8_t data[0]; /**< data feilds */
> > +} __rte_packed;
> 
> With this header, sizeof(rte_gtp_psc_hdr) = 5, is it really expected?
The data[0] is variable length data, I guess I should send another version to mention that in the comment maybe.
The header size according to the spec should be 4 octets aligned in general.
> 
> It would help to see the specification to have a better idea of how to
Sure, I've just posted the link above, please let me know of any suggestion that you have, and I'll be glad to do accordingly.

> split, but a possible solution is to do something like this:
> 
> struct rte_gtp_psc_generic_hdr {
> 	uint8_t ext_hdr_len;
> 	uint8_t type:4
> 	uint8_t qmp:1;
> 	uint8_t pad:3;
> };
> 
> struct rte_gtp_psc_<name1>_hdr {
> 	uint8_t ext_hdr_len;
> 	uint8_t type:4
> 	uint8_t qmp:1;
> 	uint8_t uint8_t snp:1;
> 	uint8_t spare_dl1:2;
> 	...
> };
> 
> ...
> 
> struct rte_gtp_psc_hdr {
> 	union {
> 		struct rte_gtp_psc_generic_hdr generic;
> 		struct rte_gtp_psc_<name1>_hdr <name1>;
> 		struct rte_gtp_psc_<name2>_hdr <name2>;
> 	};
> };
> 
> Also, you need to take care about endianness.
> 
> 
> Regards,
> Olivier
Kindest regards
Raslan Darawsheh