27. ABI and API Deprecation
See the guidelines document for details of the ABI policy. API and ABI deprecation notices are to be posted here.
27.1. Deprecation Notices
kvargs: The function
rte_kvargs_processwill get a new parameter for returning key match count. It will ease handling of no-match case.
eal: The function
rte_eal_remote_launchwill return new error codes after read or write error on the pipe, instead of calling
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 will adopt C11 atomic operations semantics and provide wrappers using C11 atomic built-ins. These wrappers 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 will adopt C11 barrier semantics and provide wrappers using C11 atomic built-ins. These wrappers 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_MAXis 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
ethdev: The flow director API, including
rte_eth_conf.fdir_conffield, and the related structures (
rte_eth_fdir_*), will be removed in DPDK 20.11.
ethdev: New offload flags
DEV_RX_OFFLOAD_FLOW_MARKwill 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_mbuffields 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.
uint32_t max_rx_pkt_lenfield of
struct rte_eth_rxmode, will be replaced by a new
uint32_t mtufield of
struct rte_eth_confin v21.11. The new
mtufield 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->mtuvariable will be used to store the configured
mtuvalue, and this new
(struct rte_eth_dev)->data->dev_conf.mtuvariable will be used to store the user configuration request. Unlike
max_rx_pkt_len, which was valid only when
mtufield will be always valid. When
mtuconfig is not provided by the application, default
RTE_ETHER_MTUvalue will be used.
(struct rte_eth_dev)->data->mtushould be updated after MTU set successfully, either by
An application may need to configure device for a specific Rx packet size, like for cases
DEV_RX_OFFLOAD_SCATTERis 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
mtucorresponding to a Rx buffer size, for this
(struct rte_eth_dev_info).max_rx_pktlenwill 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
rte_eth_rx_descriptor_donewill be removed in 21.11. Existing
rte_eth_tx_descriptor_statusAPIs can be used as replacement.
ethdev: The port mirroring API can be replaced with a more fine grain flow API. The structs
rte_eth_vlan_mirrorand the functions
rte_eth_mirror_rule_resetwill 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.
struct rte_flow_action_countis deprecated and will be removed in DPDK 21.11. Shared counters should be managed using shared actions API (
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_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_CNTRSwill be removed.
ethdev: The offload flag
PKT_RX_EIP_CKSUM_BADwill 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.
eventdev: The structure
rte_event_eth_rx_adapter_queue_confwill be extended to include
rte_event_eth_rx_adapter_event_vector_configelements and the function
rte_event_eth_rx_adapter_queue_event_vector_configwill 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_addusing the structure
sched: To allow more traffic classes, flexible mapping of pipe queues to traffic classes, and subport level configuration of pipes and queues changes will be made to macros, data structures and API functions defined in “rte_sched.h”. These changes are aligned to improvements suggested in the RFC https://mails.dpdk.org/archives/dev/2018-November/120035.html.
metrics: The function
rte_metrics_initwill have a non-void return in order to notify errors instead of calling
cmdlinestructure 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.