32. ABI and API Deprecation

See the guidelines document for details of the ABI policy. API and ABI deprecation notices are to be posted here.

32.1. 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: 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.
  • 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: Announce moving from dedicated modify function for each field, to using the general rte_flow_modify_field action.
  • ethdev: The flow API matching pattern structures, struct rte_flow_item_*, should start with relevant protocol header. Some matching pattern structures implements this by duplicating protocol header fields in the struct. To clarify the intention and to be sure protocol header is intact, will replace those fields with relevant protocol header struct. In v21.02 both individual protocol header fields and the protocol header struct will be added as union, target is switch usage to the protocol header by time. In v21.11 LTS, protocol header fields will be cleaned and only protocol header struct will remain.
  • 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 MODIFY_FIELD action. The legacy actions should be deprecated in 22.07, once MODIFY_FIELD alternative is implemented. The legacy actions should be removed in DPDK 22.11.
  • 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.
  • 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.