ABI and API Deprecation

This document details the policy for maintaining stability of SPDK ABI and API.

Major ABI version can change at most once for each quarterly SPDK release. ABI versions are managed separately for each library and follow Semantic Versioning.

API and ABI deprecation notices shall be posted in the next section. Each entry must describe what will be removed and can suggest the future use or alternative. Specific future SPDK release for the removal must be provided. ABI cannot be removed without providing deprecation notice for at least single SPDK release.

Deprecated code paths must be registered with SPDK_DEPRECATION_REGISTER() and logged with SPDK_LOG_DEPRECATED(). The tag used with these macros will appear in the SPDK log at the warn level when SPDK_LOG_DEPRECATED() is called, subject to rate limits. The tags can be matched with the level 4 headers below.

Deprecation Notices


PMDK is no longer supported and integrations with it in SPDK are now deprecated, and will be removed in SPDK 23.05. Please see: UPDATE ON PMDK AND OUR LONG TERM SUPPORT STRATEGY.


Deprecated ACCEL_FLAG_PERSISTENT flag in accel_sw accel framework module, it will be removed in SPDK 23.05.


Deprecated bdev_pmem based on libpmemblk, it will be removed in SPDK 23.05.


Reduce library will no longer depend on libpmem. pm_file_dir parameter in spdk_reduce_vol_init() will no longer point to pmem device or pmem file. Instead it will be possible to operate on a file, without the benefits of persistency.



VTune integration is in now deprecated and will be removed in SPDK 23.05.



The Open CAS Framework (OCF) integration via bdev module and env_ocf is now deprecated and will be removed in SPDK 23.05.



Deprecated spdk_nvme_ctrlr_prepare_for_reset API, which will be removed in SPDK 22.01. For PCIe transport, spdk_nvme_ctrlr_disconnect should be used before freeing I/O qpairs.



Deprecated calling spdk_bdev_register() and spdk_bdev_examine() from a thread other than the app thread. See spdk_thread_get_app_thread(). Starting in SPDK 23.05, calling spdk_bdev_register() or spdk_bdev_examine() from a thread other than the app thread will return an error.

With the removal of this deprecation, calls to vbdev modules' examine_disk() and examine_config() callbacks will happen only on the app thread. This means that vbdev module maintainers will not need to make any changes to examine callbacks that call spdk_bdev_register() on the same thread as the examine callback uses.



Deprecated the SPDK partition type GUID 7c5222bd-8f5d-4087-9c00-bf9843c7b58c. Partitions of this type have bdevs created that are one block less than the actual size of the partition. Existing partitions using the deprecated GUID can continue to use that GUID; support for the deprecated GUID will remain in SPDK indefinitely, and will continue to exhibit the off-by-one bug so that on-disk metadata layouts based on the incorrect size are not affected.

See GitHub issue 2801 for additional details on the bug.

New SPDK partition types should use GUID 6527994e-2c5a-4eec-9613-8f5944074e8b which will create a bdev of the correct size.