34. ABI and API Deprecation

See the guidelines document for details of the ABI policy.

With DPDK 23.11, there will be a new major ABI version: 24. This means that during the development of 23.11, new items may be added to structs or enums, even if those additions involve an ABI compatibility breakage.

Other API and ABI deprecation notices are to be posted below.

34.1. Deprecation Notices

  • C Compiler: From DPDK 23.11 onwards, building DPDK will require a C compiler which supports the C11 standard, including support for C11 standard atomics.

    More specifically, the requirements will be:

    • Support for flag “-std=c11” (or similar)
    • __STDC_NO_ATOMICS__ is not defined when using c11 flag

    Please note:

  • build: Enabling deprecated libraries (flow_classify, kni) won’t be possible anymore through the use of the disable_libs build option. A new build option for deprecated libraries will be introduced instead.

  • kvargs: The function rte_kvargs_process will get a new parameter for returning key match count. It will ease handling of no-match case.

  • cmdline: The function cmdline_poll does not work correctly on either Linux or Windows and is unused by any part of DPDK. This function is now deprecated and will be removed in DPDK 23.11.

  • telemetry: The functions rte_tel_data_add_array_u64 and rte_tel_data_add_dict_u64, used by telemetry callbacks for adding unsigned integer values to be returned to the user, are renamed to rte_tel_data_add_array_uint and rte_tel_data_add_dict_uint respectively. As such, the old function names are deprecated and will be removed in a future release.

  • eal: RTE_FUNC_PTR_OR_* macros have been marked deprecated and will be removed in the future. Applications can use devtools/cocci/func_or_ret.cocci to update their code.

  • eal: The functions rte_thread_setname and rte_ctrl_thread_create are planned to be deprecated starting with the 23.07 release, subject to the replacement API rte_thread_set_name and rte_thread_create_control being marked as stable, and planned to be removed by the 23.11 release.

  • eal: RTE_CPUFLAG_NUMFLAGS will be removed in DPDK 23.11 release. This is to allow new CPU features to be added without ABI breakage.

  • rte_atomicNN_xxx: These APIs do not take memory order parameter. This does not allow for writing optimized code for all the CPU architectures supported in DPDK. DPDK has adopted the atomic operations from https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html. These operations must be used for patches that need to be merged in 20.08 onwards. This change will not introduce any performance degradation.

  • rte_smp_*mb: These APIs provide full barrier functionality. However, many use cases do not require full barriers. To support such use cases, DPDK has adopted atomic operations from https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html. These operations and a new wrapper rte_atomic_thread_fence instead of __atomic_thread_fence must be used for patches that need to be merged in 20.08 onwards. This change will not introduce any performance degradation.

  • kni: The KNI kernel module and library are not recommended for use by new applications - other technologies such as virtio-user are recommended instead. Following the DPDK technical board decision and refinement, the KNI kernel module, library and PMD will be removed from the DPDK 23.11 release.

  • lib: will fix extending some enum/define breaking the ABI. There are multiple samples in DPDK that enum/define terminated with a .*MAX.* value which is used by iterators, and arrays holding these values are sized with this .*MAX.* value. So extending this enum/define increases the .*MAX.* value which increases the size of the array and depending on how/where the array is used this may break the ABI. RTE_ETH_FLOW_MAX is one sample of the mentioned case, adding a new flow type will break the ABI because of flex_mask[RTE_ETH_FLOW_MAX] array usage in following public struct hierarchy: rte_eth_fdir_flex_conf -> rte_eth_fdir_conf -> rte_eth_conf (in the middle). Need to identify this kind of usages and fix in 20.11, otherwise this blocks us extending existing enum/define. One solution can be using a fixed size array instead of .*MAX.* value.

  • ethdev: The flow API matching pattern structures, struct rte_flow_item_*, should start with relevant protocol header structure from lib/net/. The individual protocol header fields and the protocol header struct may be kept together in a union as a first migration step. In future (target is DPDK 23.11), the protocol header fields will be cleaned and only protocol header struct will remain.

    These items are not compliant (not including struct from lib/net/):

    • rte_flow_item_ah
    • rte_flow_item_e_tag
    • rte_flow_item_geneve
    • rte_flow_item_geneve_opt
    • rte_flow_item_gre
    • rte_flow_item_icmp6
    • rte_flow_item_icmp6_nd_na
    • rte_flow_item_icmp6_nd_ns
    • rte_flow_item_icmp6_nd_opt
    • rte_flow_item_icmp6_nd_opt_sla_eth
    • rte_flow_item_icmp6_nd_opt_tla_eth
    • rte_flow_item_igmp
    • rte_flow_item_ipv6_ext
    • rte_flow_item_l2tpv3oip
    • rte_flow_item_mpls
    • rte_flow_item_nsh
    • rte_flow_item_nvgre
    • rte_flow_item_pfcp
    • rte_flow_item_pppoe
    • rte_flow_item_pppoe_proto_id

  • ethdev: Queue specific stats fields will be removed from struct rte_eth_stats. Mentioned fields are: q_ipackets, q_opackets, q_ibytes, q_obytes, q_errors. Instead queue stats will be received via xstats API. Current method support will be limited to maximum 256 queues. Also compile time flag RTE_ETHDEV_QUEUE_STAT_CNTRS will be removed.

  • ethdev: Flow actions PF and VF have been deprecated since DPDK 21.11 and are yet to be removed. That still has not happened because there are net drivers which support combined use of either action PF or action VF with action QUEUE, namely, i40e, ixgbe and txgbe (L2 tunnel rule). It is unclear whether it is acceptable to just drop support for such a complex use case, so maintainers of the said drivers should take a closer look at this and provide assistance.

  • ethdev: Actions OF_DEC_NW_TTL, SET_IPV4_SRC, SET_IPV4_DST, SET_IPV6_SRC, SET_IPV6_DST, SET_TP_SRC, SET_TP_DST, DEC_TTL, SET_TTL, SET_MAC_SRC, SET_MAC_DST, INC_TCP_SEQ, DEC_TCP_SEQ, INC_TCP_ACK, DEC_TCP_ACK, SET_IPV4_DSCP, SET_IPV6_DSCP, SET_TAG, SET_META are marked as legacy and superseded by the generic RTE_FLOW_ACTION_TYPE_MODIFY_FIELD. The legacy actions should be removed once MODIFY_FIELD alternative is implemented in drivers.

  • bonding: The macro RTE_ETH_DEV_BONDED_SLAVE will be deprecated in DPDK 23.07, and removed in DPDK 23.11. The relevant code can be updated using RTE_ETH_DEV_BONDING_MEMBER. The data structure struct rte_eth_bond_8023ad_slave_info will be renamed to struct rte_eth_bond_8023ad_member_info in DPDK 23.11. The following functions will be removed in DPDK 23.11. The old functions: rte_eth_bond_8023ad_slave_info, rte_eth_bond_active_slaves_get, rte_eth_bond_slave_add, rte_eth_bond_slave_remove, and rte_eth_bond_slaves_get will be replaced by: rte_eth_bond_8023ad_member_info, rte_eth_bond_active_members_get, rte_eth_bond_member_add, rte_eth_bond_member_remove, and rte_eth_bond_members_get.

  • cryptodev: The function rte_cryptodev_cb_fn will be updated to have another parameter qp_id to return the queue pair ID which got error interrupt to the application, so that application can reset that particular queue pair.

  • cryptodev: The arrays of algorithm strings rte_crypto_cipher_algorithm_strings, rte_crypto_auth_algorithm_strings, rte_crypto_aead_algorithm_strings and rte_crypto_asym_xform_strings are deprecated and will be removed in DPDK 23.11. Application can use the new APIs rte_cryptodev_get_cipher_algo_string, rte_cryptodev_get_auth_algo_string, rte_cryptodev_get_aead_algo_string and rte_cryptodev_asym_get_xform_string respectively.

  • security: Hide structures rte_security_ops and rte_security_ctx as these are internal to DPDK library and drivers.

  • security: New SA option ingress_oop would be added in structure rte_security_ipsec_sa_options to support out of place processing for inline inbound SA from DPDK 23.11. reserved_opts field in the same struct would be removed as discussed in techboard meeting.

  • eventdev: The single-event (non-burst) enqueue and dequeue operations, used by static inline burst enqueue and dequeue functions in rte_eventdev.h, will be removed in DPDK 23.11. This simplification includes changing the layout and potentially also the size of the public rte_event_fp_ops struct, breaking the ABI. Since these functions are not called directly by the application, the API remains unaffected.

  • flow_classify: The flow_classify library and example have no maintainer. The library is experimental and, as such, it could be removed from DPDK. Its removal has been postponed to let potential users report interest in maintaining it. In the absence of such interest, this library will be removed in DPDK 23.11.

  • pipeline: The pipeline library legacy API (functions rte_pipeline_*) will be deprecated and subsequently removed in DPDK 24.11 release. Before this, the new pipeline library API (functions rte_swx_pipeline_*) will gradually transition from experimental to stable status.

  • table: The table library legacy API (functions rte_table_*) will be deprecated and subsequently removed in DPDK 24.11 release. Before this, the new table library API (functions rte_swx_table_*) will gradually transition from experimental to stable status.

  • port: The port library legacy API (functions rte_port_*) will be deprecated and subsequently removed in DPDK 24.11 release. Before this, the new port library API (functions rte_swx_port_*) will gradually transition from experimental to stable status.