40. 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.

40.1. Deprecation Notices

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

• eal: The -c <coremask> commandline parameter is deprecated and will be removed in a future release. Use the -l <corelist> or --lcores=<corelist> parameters instead to specify the cores to be used when running a DPDK application.

• eal: The -s <service-coremask> commandline parameter is deprecated and will be removed in a future release. Use the -S <service-corelist> parameter instead to specify the cores to be used for background services in DPDK.

• 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.

• 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.

• net, ethdev: The flow item RTE_FLOW_ITEM_TYPE_VXLAN_GPE is replaced with RTE_FLOW_ITEM_TYPE_VXLAN. The struct rte_flow_item_vxlan_gpe and its mask rte_flow_item_vxlan_gpe_mask are replaced with rte_flow_item_vxlan and rte_flow_item_vxlan_mask. The flow item RTE_FLOW_ITEM_TYPE_VXLAN_GPE, the structs rte_flow_item_vxlan_gpe, rte_flow_item_vxlan_gpe_mask, and the header struct rte_vxlan_gpe_hdr with the macro RTE_ETHER_VXLAN_GPE_HLEN will be removed in DPDK 25.11.

• ethdev: The queue stats mapping functions rte_eth_dev_set_tx_queue_stats_mapping and rte_eth_dev_set_rx_queue_stats_mapping are deprecated and will be removed in a future release. Following the removal of queue statistics from the main ethdev statistics structure, these functions are no longer needed.

• 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: 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.

• 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.

• bus/vmbus: Starting DPDK 25.11, all the vmbus API defined in drivers/bus/vmbus/rte_bus_vmbus.h will become internal to DPDK. Those API functions are used internally by DPDK core and netvsc PMD.

• net/intel: Drivers that have an SSE vector path alongside other vector paths, namely i40e, iavf and ice, will have their SSE vector paths removed in DPDK 25.11. Modern x86 systems all support AVX2, if not AVX-512, so the SSE path is no longer widely used. This change will not result in any feature loss, as the fallback scalar paths which have feature parity with SSE will be used in the cases where the SSE paths would have been used.

• net/mlx5: repr_matching_en device argument is deprecated and will be removed in DPDK 25.11 release. With disabled representor matching, behavior of Rx datapath in mlx5 PMD is incompatible with current DPDK representor model. Packets from any E-Switch port can arrive on any representor, depending only on created flow rules. Such working model should be exposed directly in DPDK ethdev API, without relying on flow API. Currently there is no alternative API providing the same functionality as with repr_matching_en set to 0.