28. ABI and API Deprecation

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

28.1. 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 function rte_eal_remote_launch will return new error codes after read or write error on the pipe, instead of calling rte_panic.

• eal: The lcore state FINISHED will be removed from the enum rte_lcore_state_t. The lcore state WAIT is enough to represent the same state.

• eal: Making struct rte_intr_handle internal to avoid any ABI breakages in future.

• 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.

• mbuf: The mbuf offload flags PKT_* will be renamed as RTE_MBUF_F_*. A compatibility layer will be kept until DPDK 22.11, except for the flags that are already deprecated (PKT_RX_L4_CKSUM_BAD, PKT_RX_IP_CKSUM_BAD, PKT_RX_EIP_CKSUM_BAD, PKT_TX_QINQ_PKT) which will be removed.

• pci: To reduce unnecessary ABIs exposed by DPDK bus driver, “rte_bus_pci.h” will be made internal in 21.11 and macros/data structures/functions defined in the header will not be considered as ABI anymore. This change is inspired by the RFC https://patchwork.dpdk.org/project/dpdk/list/?series=17176.

• 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_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: Will add RTE_ETH_ prefix to all ethdev macros/enums in v21.11. Macros will be added for backward compatibility. Backward compatibility macros will be removed on v22.11. A few old backward compatibility macros from 2013 that does not have proper prefix will be removed on v21.11.

• ethdev: The flow director API, including rte_eth_conf.fdir_conf field, and the related structures (rte_fdir_* and rte_eth_fdir_*), will be removed in DPDK 20.11.

• ethdev: New offload flags DEV_RX_OFFLOAD_FLOW_MARK will be added in 19.11. This will allow application to enable or disable PMDs from updating rte_mbuf::hash::fdir. This scheme will allow PMDs to avoid writes to rte_mbuf fields on Rx and thereby improve Rx performance if application wishes do so. In 19.11 PMDs will still update the field even when the offload is not enabled.

• ethdev: uint32_t max_rx_pkt_len field of struct rte_eth_rxmode, will be replaced by a new uint32_t mtu field of struct rte_eth_conf in v21.11. The new mtu field will be used to configure the initial device MTU via rte_eth_dev_configure() API. Later MTU can be changed by rte_eth_dev_set_mtu() API as done now. The existing (struct rte_eth_dev)->data->mtu variable will be used to store the configured mtu value, and this new (struct rte_eth_dev)->data->dev_conf.mtu variable will be used to store the user configuration request. Unlike max_rx_pkt_len, which was valid only when JUMBO_FRAME enabled, mtu field will be always valid. When mtu config is not provided by the application, default RTE_ETHER_MTU value will be used. (struct rte_eth_dev)->data->mtu should be updated after MTU set successfully, either by rte_eth_dev_configure() or rte_eth_dev_set_mtu().

  An application may need to configure device for a specific Rx packet size, like for cases DEV_RX_OFFLOAD_SCATTER is not supported and device received packet size can’t be bigger than Rx buffer size. To cover these cases an application needs to know the device packet overhead to be able to calculate the mtu corresponding to a Rx buffer size, for this (struct rte_eth_dev_info).max_rx_pktlen will be kept, the device packet overhead can be calculated as: (struct rte_eth_dev_info).max_rx_pktlen - (struct rte_eth_dev_info).max_mtu

• ethdev: rx_descriptor_done dev_ops and rte_eth_rx_descriptor_done will be removed in 21.11. Existing rte_eth_rx_descriptor_status and rte_eth_tx_descriptor_status APIs can be used as replacement.

• ethdev: The port mirroring API can be replaced with a more fine grain flow API. The structs rte_eth_mirror_conf, rte_eth_vlan_mirror and the functions rte_eth_mirror_rule_set, rte_eth_mirror_rule_reset will be marked as deprecated in DPDK 20.11, along with the associated macros ETH_MIRROR_*. This API will be fully removed in DPDK 21.11.

• ethdev: Announce moving from dedicated modify function for each field, to using the general rte_flow_modify_field action.

• ethdev: The struct rte_flow_action_modify_data will be modified to support modifying fields larger than 64 bits. In addition, documentation will be updated to clarify byte order.

• ethdev: Attribute shared of the struct rte_flow_action_count is deprecated and will be removed in DPDK 21.11. Shared counters should be managed using shared actions API (rte_flow_shared_action_create etc).

• ethdev: Definition of the flow API action RTE_FLOW_ACTION_TYPE_PORT_ID is ambiguous and needs clarification. Structure rte_flow_action_port_id will be extended to specify traffic direction to the represented entity or ethdev port itself in DPDK 21.11.

• ethdev: Flow API documentation is unclear if ethdev port used to create a flow rule adds any implicit match criteria in the case of transfer rules. The semantics will be clarified in DPDK 21.11 and it will require fixes in drivers and applications which interpret it in a different way.

• 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: Add new Rx queue offload flag RTE_ETH_RX_OFFLOAD_SHARED_RXQ and shared_group field to struct rte_eth_rxconf.

• 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: The offload flag PKT_RX_EIP_CKSUM_BAD will be removed and replaced by the new flag PKT_RX_OUTER_IP_CKSUM_BAD. The new name is more consistent with existing outer header checksum status flag naming, which should help in reducing confusion about its usage.

• i40e: As there are both i40evf and iavf pmd, the functions of them are duplicated. And now more and more advanced features are developed on iavf. To keep consistent with kernel driver’s name (https://patchwork.ozlabs.org/patch/970154/), i40evf is no need to maintain. Starting from 21.05, the default VF driver of i40e will be iavf, but i40evf can still be used if users specify the devarg “driver=i40evf”. I40evf will be deleted in DPDK 21.11.

• net: s_addr and d_addr fields of rte_ether_hdr structure will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets headers.

• net: The structure rte_ipv4_hdr will have two unions. The first union is for existing version_ihl byte and new bitfield for version and IHL. The second union is for existing fragment_offset and new bitfield for fragment flags and offset.

• vhost: rte_vdpa_register_device, rte_vdpa_unregister_device, rte_vhost_host_notifier_ctrl and rte_vdpa_relay_vring_used vDPA driver interface will be marked as internal in DPDK v21.11.

• vhost: rename struct vhost_device_ops to struct rte_vhost_device_ops in DPDK v21.11.

• vhost: The experimental tags of rte_vhost_driver_get_protocol_features, rte_vhost_driver_get_queue_num, rte_vhost_crypto_create, rte_vhost_crypto_free, rte_vhost_crypto_fetch_requests, rte_vhost_crypto_finalize_requests, rte_vhost_crypto_set_zero_copy, rte_vhost_va_from_guest_pa, rte_vhost_extern_callback_register, and rte_vhost_driver_set_protocol_features functions will be removed and the API functions will be made stable in DPDK 21.11.

• compressdev: min and max fields of rte_param_log2_range structure will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets headers.

• cryptodev: min and max fields of rte_crypto_param_range structure will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets headers.

• cryptodev: The field dataunit_len of the struct rte_crypto_cipher_xform has a limited size uint16_t. It will be moved and extended as uint32_t in DPDK 21.11.

• cryptodev: The structure rte_crypto_sym_vec would be updated to add dest_sgl to support out of place processing. This field will be null for inplace processing. This change is targeted for DPDK 21.11.

• cryptodev: The structure rte_crypto_vec would be updated to add tot_len to support total buffer length. This is required for security cases like IPsec and PDCP encryption offload to know how much additional memory space is available in buffer other than data length so that driver/HW can write expanded size data after encryption. This change is targeted for DPDK 21.11.

• cryptodev: Hide structures rte_cryptodev_sym_session and rte_cryptodev_asym_session to remove unnecessary indirection between session and the private data of session. An opaque pointer can be exposed directly to application which can be attached to the rte_crypto_op.

• cryptodev: The interface between library and drivers will be marked as internal in DPDK 21.11.

• security: Hide structure rte_security_session and expose an opaque pointer for the private data to the application which can be attached to the packet while enqueuing.

• security: The IPsec configuration structure struct rte_security_ipsec_xform will be updated with new members to allow SA lifetime configuration. A new structure would be introduced to replace the current member, esn_soft_limit.

• security: The structure rte_security_ipsec_xform will be extended with multiple fields: source and destination port of UDP encapsulation, IPsec payload MSS (Maximum Segment Size), and ESN (Extended Sequence Number).

• security: The IPsec SA config options struct rte_security_ipsec_sa_options will be updated with new fields to support new features like IPsec inner checksum, tunnel header verification, TSO in case of protocol offload.

• ipsec: The structure rte_ipsec_sa_prm will be extended with a new field hdr_l3_len to configure tunnel L3 header length.

• eventdev: The file rte_eventdev_pmd.h will be renamed to eventdev_driver.h to make the driver interface as internal and the structures rte_eventdev_data, rte_eventdev and rte_eventdevs will be moved to a new file named rte_eventdev_core.h in DPDK 21.11. The rte_ prefix for internal structures and functions will be removed across the library. The experimental eventdev trace APIs and rte_event_vector_pool_create, rte_event_eth_rx_adapter_vector_limits_get will be promoted to stable. An 8-byte reserved field will be added to the structure rte_event_timer to support future extensions.

• eventdev: The structure rte_event_eth_rx_adapter_queue_conf will be extended to include rte_event_eth_rx_adapter_event_vector_config elements and the function rte_event_eth_rx_adapter_queue_event_vector_config will be removed in DPDK 21.11.

  An application can enable event vectorization by passing the desired vector values to the function rte_event_eth_rx_adapter_queue_add using the structure rte_event_eth_rx_adapter_queue_add.

• eventdev: Reserved bytes of rte_event_crypto_request is a space holder for response_info. Both should be decoupled for better clarity. New space for response_info can be made by changing rte_event_crypto_metadata type to structure from union. This change is targeted for DPDK 21.11.

• metrics: The function rte_metrics_init will have a non-void return in order to notify errors instead of calling rte_exit.

• cmdline: cmdline structure will be made opaque to hide platform-specific content. On Linux and FreeBSD, supported prior to DPDK 20.11, original structure will be kept until DPDK 21.11.

• security: The functions rte_security_set_pkt_metadata and rte_security_get_userdata will be made inline functions and additional flags will be added in structure rte_security_ctx in DPDK 21.11.

• cryptodev: The structure rte_crypto_op would be updated to reduce reserved bytes to 2 (from 3), and use 1 byte to indicate warnings and other information from the crypto/security operation. This field will be used to communicate events such as soft expiry with IPsec in lookaside mode.