24. ABI and API Deprecation
See the guidelines document for details of the ABI policy. API and ABI deprecation notices are to be posted here.
24.1. Deprecation Notices
make: Support for building DPDK with “make” has been deprecated and support will be removed in the 20.11 release. From 20.11 onwards, DPDK should be built using meson and ninja. For basic instructions see the Quick-start Guide on the website or the Getting Started Guide document.
meson: The minimum supported version of meson for configuring and building DPDK will be increased to v0.47.1 (from 0.41) from DPDK 19.05 onwards. For those users with a version earlier than 0.47.1, an updated copy of meson can be got using the
pip3, tool for downloading python packages.
build macros: The macros defining RTE_MACHINE_CPUFLAG_* will be removed from the build. The information provided by these macros is available through standard compiler macros. For example, RTE_MACHINE_CPUFLAG_SSE3 duplicates the compiler-provided macro __SSE3__.
kvargs: The function
rte_kvargs_processwill get a new parameter for returning key match count. It will ease handling of no-match case.
eal: To be more inclusive in choice of naming, the DPDK project will replace uses of master/slave in the API’s and command line arguments.
References to master/slave in relation to lcore will be renamed to initial/worker. The function
rte_get_master_lcore()will be renamed to
rte_get_initial_lcore(). For the 20.11 release, both names will be present and the old function will be marked with the deprecated tag. The old function will be removed in a future version.
The iterator for worker lcores will also change:
RTE_LCORE_FOREACH_SLAVEwill be replaced with
master-lcoreargument to testpmd will be replaced with
initial-lcore. The old
master-lcoreargument will produce a runtime notification in 20.11 release, and be removed completely in a future release.
eal: The terms blacklist and whitelist to describe devices used by DPDK will be replaced in the 20.11 relase. This will apply to command line arguments as well as macros.
RTE_DEV_BLACKLISTEDwill be replaced with
RTE_DEV_WHITELISTEDwill be replaced with
RTE_BUS_SCAN_WHITELISTwill be replaced with
RTE_DEVTYPE_WHITELISTED_PCIwill be replaced with
The old macros will be marked as deprecated in 20.11 and any usage will cause a compile warning. They will be removed in a future release.
The command line arguments to
rte_eal_initwill change from
-i, --include. The old command line arguments will continue to be accepted in 20.11 but will cause a runtime warning message. The old arguments will be removed in a future release.
eal: The function
rte_eal_remote_launchwill return new error codes after read or write error on the pipe, instead of calling
rte_logsstruct and global symbol will be made private to remove it from the externally visible ABI and allow it to be updated in the future.
rte_dev_eventstructure will be made private to the EAL as no public API makes use of it.
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.
rte_cio_*mb: Since the IO barriers for ARMv8 platforms are relaxed from DSB to DMB, rte_cio_*mb APIs provide the same functionality as rte_io_*mb APIs (taking all platforms into consideration). rte_io_*mb APIs should be used in the place of rte_cio_*mb APIs. The rte_cio_*mb APIs will be deprecated in 20.11 release.
igb_uio: In the view of reducing the kernel dependency from the main tree, as a first step, the Technical Board decided to move
igb_uiokernel module to the dpdk-kmods repository in the /linux/igb_uio/ directory in 20.11. Minutes of Technical Board Meeting of 2019-11-06.
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
pci: The PCI resources map API (
pci_unmap_resource) was not abstracting the Unix mmap flags (see the workaround for Windows support implemented in the commit 9d2b24593724 (“pci: keep API compatibility with mmap values”)). This API will be removed from the public API in 20.11 and moved to the PCI bus driver along with the PCI resources lists and associated structures (
mapped_pci_res_list). With this removal, there won’t be a need for the mentioned workaround which will be reverted.
rte_kernel_driverenum defined in rte_dev.h will be made private to the PCI subsystem as it is used only by the PCI bus driver and PCI drivers. The associated field
kdrvin the ethdev
rte_eth_dev_datastructure will be removed as it gave no useful abstracted information to the applications and had no user (neither internal nor external).
mbuf: Some fields will be converted to dynamic API in DPDK 20.11 in order to reserve more space for the dynamic fields, as explained in this presentation. The following static fields will be moved as dynamic:
As a consequence, the layout of the
struct rte_mbufwill be re-arranged, avoiding impact on vectorized implementation of the driver datapaths, while evaluating performance gains of a better use of the first cache line.
The deprecated unioned fields
refcnt_atomic(as explained below) will be removed in DPDK 20.11.
refcnt_atomicmember in structures
rte_mbuf_ext_shared_infois of type
rte_atomic16_t. Due to adoption of C11 atomic builtins, the field
refcnt_atomicwill be replaced with
uint16_tin DPDK 20.11.
ethdev: Split the
struct eth_dev_opsstruct to hide it as much as possible will be done in 20.11. Currently the
struct eth_dev_opsstruct is accessible by the application because some inline functions, like
rte_eth_tx_descriptor_status(), access the struct directly. The struct will be separate in two, the ops used by inline functions will be moved next to Rx/Tx burst functions, rest of the
struct eth_dev_opsstruct will be moved to header file for drivers to hide it from applications.
ethdev: the legacy filter API, including
rte_eth_dev_filter_ctrl()as well as filter types MACVLAN, ETHERTYPE, FLEXIBLE, SYN, NTUPLE, TUNNEL, FDIR, HASH and L2_TUNNEL, is superseded by the generic flow API (rte_flow) in PMDs that implement the latter. The legacy API will be removed in DPDK 20.11.
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: The legacy L2 tunnel filtering API is deprecated as the rest of the legacy filtering API. The functions
rte_eth_dev_l2_tunnel_offload_setwhich were not marked as deprecated, will be removed in DPDK 20.11.
ethdev: Update API functions returning
intwith negative errno values to indicate various error conditions (e.g. invalid port ID, unsupported operation, failed operation):
ethdev: The temporary flag RTE_ETH_DEV_CLOSE_REMOVE will be removed in 20.11. As a consequence, the new behaviour introduced in 18.11 will be effective for all drivers: generic port resources are freed on close operation. Private resources are expected to be released in the
dev_closecallback. More details in http://inbox.dpdk.org/dev/5248162.j6AOsuQRmx@thomas/
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.
ethdev: Add new fields to
rte_eth_rxconfto configure the receiving queues to split ingress packets into multiple segments according to the specified lengths into the buffers allocated from the specified memory pools. The backward compatibility to existing API is preserved.
struct rte_eth_rxq_infowill be modified to include a new optional field, indicating the buffer size used in receiving packets for HW. This change is planned for 20.11. For more details: https://mails.dpdk.org/archives/dev/2020-July/176135.html.
rte_eth_rx_descriptor_donewill be deprecated in 20.11 and will 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_item_vlanstructs will be modified, to include an additional value, indicating existence or absence of a VLAN header following the current header, as proposed in RFC https://mails.dpdk.org/archives/dev/2020-August/177536.html.
struct rte_flow_item_ipv6struct will be modified to include additional values, indicating existence or absence of IPv6 extension headers following the IPv6 header, as proposed in RFC https://mails.dpdk.org/archives/dev/2020-August/177257.html.
ethdev: Some internal APIs for driver usage are exported in the .map file. Now DPDK has
__rte_internalmarker so we can mark internal APIs and move them to the INTERNAL block in .map. Although these APIs are internal it will break the ABI checks, that is why change is planned for 20.11. The list of internal APIs are mainly ones listed in
traffic manager: All traffic manager API’s in
rte_tm.hwere mistakenly made ABI stable in the v19.11 release. The TM maintainer and other contributors have agreed to keep the TM APIs as experimental in expectation of additional spec improvements. Therefore, all APIs in
rte_tm.hwill be marked back as experimental in v20.11 DPDK release. For more details, please see the thread.
pmd_dpaa: The API
rte_pmd_dpaa_set_tx_loopbackwill have extended
vhost: Vhost-user dequeue zero-copy support will be removed in 20.11. The only known user is OVS where the feature is still experimental, and has not received any update for 2.5 years. This feature faces reliability issues and is often conflicting with new features being implemented.
security: The API
rte_security_session_createtakes only single mempool for session and session private data. So the application need to create mempool for twice the number of sessions needed and will also lead to wastage of memory as session private data need more memory compared to session. Hence the API will be modified to take two mempool pointers - one for session and one for private data.
enum rte_crypto_auth_algorithmwill be removed.
cryptodev: support for using IV with all sizes is added, J0 still can be used but only when IV length in following structs
rte_crypto_aead_xformis set to zero. When IV length is greater or equal to one it means it represents IV, when is set to zero it means J0 is used directly, in this case 16 bytes of J0 need to be passed.
eventdev: Following structures will be modified to support DLB PMD and future extensions:
Patches containing justification, documentation, and proposed modifications can be found at:
rawdev: The rawdev APIs which take a device-specific structure as parameter directly, or indirectly via a “private” pointer inside another structure, will be modified to take an additional parameter of the structure size. The affected APIs will include
RTE_ACL_CLASSIFY_NUMenum value will be removed. This enum value is not used inside DPDK, while it prevents to add new classify algorithms without causing an ABI breakage.
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.
sched: To allow dynamic configuration of the subport bandwidth profile, changes will be made to data structures
rte_sched_port_paramsand new data structure, API functions will be defined in
rte_sched.h. These changes are aligned as suggested in the RFC https://mails.dpdk.org/archives/dev/2020-July/175161.html
metrics: The function
rte_metrics_initwill have a non-void return in order to notify errors instead of calling
rte_power_set_envfunction will no longer return 0 on attempt to set new power environment if power environment was already initialized. In this case the function will return -1 unless the environment is unset first (using
rte_power_unset_env). Other function usage scenarios will not change.
python: Since the beginning of 2020, Python 2 has officially reached end-of-support: https://www.python.org/doc/sunset-python-2/. Python 2 support will be completely removed in 20.11. In 20.08, explicit deprecation warnings will be displayed when running scripts with Python 2.
dpdk-setup.sh: This old script relies on deprecated stuff, and especially
make. Given environments are too much variables for such a simple script, it will be removed in DPDK 20.11. Some useful parts may be converted into specific scripts.