@@ -53,6 +53,9 @@ year's November (X.11) release will be maintained as an LTS for 2 years.
After the X.11 release, an LTS branch will be created for it at
http://git.dpdk.org/dpdk-stable where bugfixes will be backported to.
+A LTS release may align with the declaration of a new major ABI version,
+please read the `DPDK ABI/API policy`_ for more information.
+
It is anticipated that there will be at least 4 releases per year of the LTS
or approximately 1 every 3 months. However, the cadence can be shorter or
longer depending on the number and criticality of the backported
@@ -119,10 +122,3 @@ A Stable Release will be released by:
list.
Stable releases are available on the `dpdk.org download page <http://core.dpdk.org/download/>`_.
-
-
-ABI
----
-
-The Stable Release should not be seen as a way of breaking or circumventing
-the DPDK ABI policy.
@@ -12,20 +12,23 @@ This document details some methods for handling ABI management in the DPDK.
General Guidelines
------------------
-#. Whenever possible, ABI should be preserved
-#. ABI/API may be changed with a deprecation process
-#. The modification of symbols can generally be managed with versioning
-#. Libraries or APIs marked in ``experimental`` state may change without constraint
-#. New APIs will be marked as ``experimental`` for at least one release to allow
- any issues found by users of the new API to be fixed quickly
-#. The addition of symbols is generally not problematic
-#. The removal of symbols generally is an ABI break and requires bumping of the
- LIBABIVER macro
-#. Updates to the minimum hardware requirements, which drop support for hardware which
- was previously supported, should be treated as an ABI change.
-
-What is an ABI
-~~~~~~~~~~~~~~
+#. Major ABI versions are declared every **two years** and are then supported
+ for two years, typically aligned with the LTS release.
+#. ABI versioning is managed at a project level in DPDK, with the supported ABI
+ version reflected in all library's soname.
+#. The ABI should be preserved and not changed lightly. The ABI may be changed
+ following the outlined deprecation process.
+#. The addition of symbols is generally not problematic. The modification of
+ symbols should be managed with ABI versioning.
+#. The removal of symbols is considered an ABI breakage, once approved these
+ will form part of the next ABI version.
+#. Libraries or APIs marked as ``experimental`` are not considered part of the
+ major ABI version and may change without constraint.
+#. Updates to the minimum hardware requirements, which drop support for hardware
+ which was previously supported, should be treated as an ABI change.
+
+What is an ABI?
+~~~~~~~~~~~~~~~
An ABI (Application Binary Interface) is the set of runtime interfaces exposed
by a library. It is similar to an API (Application Programming Interface) but
@@ -37,30 +40,55 @@ Therefore, in the case of dynamic linking, it is critical that an ABI is
preserved, or (when modified), done in such a way that the application is unable
to behave improperly or in an unexpected fashion.
+What is a library's soname?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+System libraries usually adopt the familiar major and minor version naming
+convention, where major versions (e.g. ``librte_a 1.x, 2.x``) are presumed to be
+ABI incompatible with each other and minor versions (e.g. ``librte_a 2.11,
+2.12``) are presumed to be ABI compatible. A library's `soname
+<https://en.wikipedia.org/wiki/Soname>`_. is typically used to provide backward
+compatibility information about a given library, describing the lowest common
+denominator ABI supported by the library. The soname is typically comprised of
+the library's name and major version e.g. ``librte_a.so.20``.
+
+During an application's build process, a library's soname is noted as a runtime
+dependency of the application. This information is then used by the `dynamic
+linker <https://en.wikipedia.org/wiki/Dynamic_linker>`_ when resolving the
+applications dependencies at runtime, to load a library supporting the correct
+ABI version. The library loaded at runtime therefore, may be a minor revision
+supporting the same major abi version (e.g. ``librte_a 20.12``), as the library
+used to link the application (e.g ``librte_a 20.0``).
-ABI/API Deprecation
+The DPDK ABI policy
-------------------
-The DPDK ABI policy
-~~~~~~~~~~~~~~~~~~~
+A major ABI version is declared every two years, aligned with that years LTS
+release, e.g. v19.11 . This ABI version is then supported for two years by all
+subsequent releases within that time period, typically including the next LTS
+release, e.g. v20.11.
+
+At the declaration of a major ABI version, major version numbers encoded in
+libraries soname's are bumped to indicate the new version, with minor version
+reset to 0. An example would be ``librte_a.so.20.5`` would become
+``librte_a.so.21.0``
-ABI versions are set at the time of major release labeling, and the ABI may
-change multiple times, without warning, between the last release label and the
-HEAD label of the git tree.
+The ABI may change then multiple times, without warning, between the last major
+ABI version increment and the HEAD label of the git tree, with the condition
+that ABI compatibility with the major ABI version is preserved and therefore
+soname's do not change.
-ABI versions, once released, are available until such time as their
-deprecation has been noted in the Release Notes for at least one major release
-cycle. For example consider the case where the ABI for DPDK 2.0 has been
-shipped and then a decision is made to modify it during the development of
-DPDK 2.1. The decision will be recorded in the Release Notes for the DPDK 2.1
-release and the modification will be made available in the DPDK 2.2 release.
+ABI versions, are supported by each release until such time as the next major
+ABI version is declared. At that time, the deprecation of the previous major ABI
+version will be noted in the Release Notes with guidance on individual symbol
+depreciation and upgrade notes provided.
-ABI versions may be deprecated in whole or in part as needed by a given
-update.
+ABI Changes
+~~~~~~~~~~~
-Some ABI changes may be too significant to reasonably maintain multiple
-versions. In those cases ABI's may be updated without backward compatibility
-being provided. The requirements for doing so are:
+The ABI may still change after the declaration of a major ABI version, that is
+new APIs may be still added or existing APIs may be modified. The requirements
+for doing so are:
#. At least 3 acknowledgments of the need to do so must be made on the
dpdk.org mailing list.
@@ -69,81 +97,156 @@ being provided. The requirements for doing so are:
no maintainer is available for the component, the tree/sub-tree maintainer
for that component must acknowledge the ABI change instead.
+ - The acknowledgment of a member of the technical board, as a delegate of the
+ `technical board <https://core.dpdk.org/techboard/>`_ acknowledging the
+ need for the ABI change, is also mandatory.
+
- It is also recommended that acknowledgments from different "areas of
interest" be sought for each deprecation, for example: from NIC vendors,
CPU vendors, end-users, etc.
-#. The changes (including an alternative map file) can be included with
- deprecation notice, in wrapped way by the ``RTE_NEXT_ABI`` option,
- to provide more details about oncoming changes.
- ``RTE_NEXT_ABI`` wrapper will be removed when it become the default ABI.
- More preferred way to provide this information is sending the feature
- as a separate patch and reference it in deprecation notice.
+#. Backward compatibly with the major ABI version must be maintained through
+ `ABI versioning`_, with forward-only compatibility offered for any ABI
+ changes that are indicated to be part of the next ABI version.
+
+ - In situations where backward compatibility is not possible, read the
+ section `ABI Breakages`_.
+
+ - No backward or forward compatibility is offered for API changes marked as
+ ``experimental``, as described in the section `Experimental APIs`_.
+
+#. If a newly proposed API functionally replaces an existing one, when the new
+ API becomes non-experimental then the old one is marked with
+ ``__rte_deprecated``.
+
+ - The depreciated API should follow the notification process to be removed,
+ see `Examples of Deprecation Notices`_;
+
+ - At the declaration of the next major ABI version, those ABI changes then
+ become a formal part of the new ABI and the requirement to preserve ABI
+ compatibility with the last major ABI version is then dropped.
-#. A full deprecation cycle, as explained above, must be made to offer
- downstream consumers sufficient warning of the change.
+.. note::
-Note that the above process for ABI deprecation should not be undertaken
-lightly. ABI stability is extremely important for downstream consumers of the
-DPDK, especially when distributed in shared object form. Every effort should
-be made to preserve the ABI whenever possible. The ABI should only be changed
-for significant reasons, such as performance enhancements. ABI breakage due to
-changes such as reorganizing public structure fields for aesthetic or
-readability purposes should be avoided.
+ Note that the above process for ABI deprecation should not be undertaken
+ lightly. ABI stability is extremely important for downstream consumers of the
+ DPDK, especially when distributed in shared object form. Every effort should
+ be made to preserve the ABI whenever possible. The ABI should only be changed
+ for significant reasons, such as performance enhancements. ABI breakage due
+ to changes such as reorganizing public structure fields for aesthetic or
+ readability purposes should be avoided.
+
+.. note::
+
+ Note that forward-only compatibility is offered for those changes made
+ between major ABI versions. The soname however only describes compatibility
+ with the last major ABI version and until the next major ABI version is
+ declared, these changes therefore cannot be resolved as a runtime dependency
+ through the soname. Therefore any application wishing to make use of these
+ ABI changes can only ensure that it's runtime dependencies are met through
+ Operating System package versioning.
.. note::
Updates to the minimum hardware requirements, which drop support for hardware
which was previously supported, should be treated as an ABI change, and
- follow the relevant deprecation policy procedures as above: 3 acks and
- announcement at least one release in advance.
+ follow the relevant deprecation policy procedures as above: 3 acks, technical
+ board approval and announcement at least one release in advance.
+
+
+ABI Breakages
+^^^^^^^^^^^^^
+
+For those ABI changes that may be too significant to reasonably maintain
+multiple versions. In those cases, ABIs may be updated without backward
+compatibility being provided.
+
+The additional requirements to approve an ABI breakage, on top of those
+described in the section `ABI Changes`_ are:
+
+#. ABI breaking changes (including an alternative map file) can be included with
+ deprecation notice, in wrapped way by the ``RTE_NEXT_ABI`` option, to provide
+ more details about oncoming changes. ``RTE_NEXT_ABI`` wrapper will be removed
+ at the declaration of the next major ABI version.
+
+#. Once approved and after the depreciation notice has been observed these
+ changes will form part of the next declared major ABI version.
+
+Examples of ABI Changes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+The following are examples of allowable ABI changes occurring between
+declarations of major ABI versions.
+
+* DPDK 20.0 release defines the function ``rte_foo()``, and ``rte_foo()``
+ is part of the major ABI version DPDK 20.0.
+
+* DPDK 20.2 release defines a new function ``rte_foo(uint8_t bar)``, and
+ this is not a problem as long as the symbol ``rte_foo@DPDK20.0`` is
+ preserved through `ABI versioning`_.
+
+ - The new function may be marked with the ``__rte_experimental`` tag for a
+ number of releases, as described in the section `Experimental APIs`_;
+
+ - Once ``rte_foo(uint8_t bar)`` becomes non-experimental ``rte_foo()`` is then
+ declared as ``__rte_depreciated``, with an associated deprecation notice
+ provided.
+
+* DPDK 20.1 is not re-released to include ``rte_foo(uint8_t bar)``, the new
+ version of ``rte_foo`` only exists from DPDK 20.2 onwards (forward-only
+ compatibility).
+
+* DPDK 20.1 release defines the experimental function ``__rte_experimental
+ rte_baz()``. This function may or may not exist in DPDK 20.2 and DPDK 21.0
+ releases.
+
+* An application ``dPacket`` wishes to use ``rte_foo(uint8_t bar)``, before the
+ declaration of the DPDK 21.0 major API version. The application can only
+ ensure it's runtime dependencies are met by specifying ``DPDK (>= 20.2)`` as
+ an explicit package dependency, as the soname only may only indicate the
+ supporting major ABI version.
+
+* At DPDK 21.0 release the function ``rte_foo(uint8_t bar)`` becomes
+ formally part of the major ABI version DPDK 21.0 and ``rte_foo()`` may be
+ removed.
+
Examples of Deprecation Notices
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following are some examples of ABI deprecation notices which would be
added to the Release Notes:
-* The Macro ``#RTE_FOO`` is deprecated and will be removed with version 2.0,
+* The Macro ``#RTE_FOO`` is deprecated and will be removed with version 21.0,
to be replaced with the inline function ``rte_foo()``.
* The function ``rte_mbuf_grok()`` has been updated to include a new parameter
- in version 2.0. Backwards compatibility will be maintained for this function
- until the release of version 2.1
+ in version 20.2. Backwards compatibility will be maintained for this function
+ until the release of DPDK version 21.0
-* The members of ``struct rte_foo`` have been reorganized in release 2.0 for
+* The members of ``struct rte_foo`` have been reorganized in release 20.1 for
performance reasons. Existing binary applications will have backwards
- compatibility in release 2.0, while newly built binaries will need to
+ compatibility in release 20.1, while newly built binaries will need to
reference the new structure variant ``struct rte_foo2``. Compatibility will
- be removed in release 2.2, and all applications will require updating and
+ be removed in release 21.0, and all applications will require updating and
rebuilding to the new structure at that time, which will be renamed to the
original ``struct rte_foo``.
* Significant ABI changes are planned for the ``librte_dostuff`` library. The
- upcoming release 2.0 will not contain these changes, but release 2.1 will,
+ upcoming release 20.1 will not contain these changes, but release 21.0 will,
and no backwards compatibility is planned due to the extensive nature of
- these changes. Binaries using this library built prior to version 2.1 will
+ these changes. Binaries using this library built prior to version 21.0 will
require updating and recompilation.
-New API replacing previous one
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-If a new API proposed functionally replaces an existing one, when the new API
-becomes non-experimental then the old one is marked with ``__rte_deprecated``.
-Deprecated APIs are removed completely just after the next LTS.
-
-Reminder that old API should follow deprecation process to be removed.
-
-
Experimental APIs
-----------------
-APIs marked as ``experimental`` are not considered part of the ABI and may
-change without warning at any time. Since changes to APIs are most likely
-immediately after their introduction, as users begin to take advantage of
-those new APIs and start finding issues with them, new DPDK APIs will be
-automatically marked as ``experimental`` to allow for a period of stabilization
-before they become part of a tracked ABI.
+APIs marked as ``experimental`` are not considered part of an ABI version and
+may change without warning at any time. Since changes to APIs are most likely
+immediately after their introduction, as users begin to take advantage of those
+new APIs and start finding issues with them, new DPDK APIs will be automatically
+marked as ``experimental`` to allow for a period of stabilization before they
+become part of a tracked ABI version.
Note that marking an API as experimental is a multi step process.
To mark an API as experimental, the symbols which are desired to be exported
@@ -167,34 +270,97 @@ one release. Thereafter, normal process of posting patch for review to mailing
list can be followed.
-Library versioning
-------------------
+ABI Versioning
+--------------
-Downstreams might want to provide different DPDK releases at the same time to
-support multiple consumers of DPDK linked against older and newer sonames.
+Major ABI versions
+~~~~~~~~~~~~~~~~~~
-Also due to the interdependencies that DPDK libraries can have applications
-might end up with an executable space in which multiple versions of a library
-are mapped by ld.so.
+An ABI version change to a given library, especially in core libraries such as
+``librte_mbuf``, may cause an implicit ripple effect on the ABI of it's
+dependent libraries, causing ABI breakages. There may however be no explicit
+reason to bump a dependent libraries ABI version, as there may have been no
+obvious change to the dependent library's API, even though the library's ABI
+compatibility will have been broken.
-Think of LibA that got an ABI bump and LibB that did not get an ABI bump but is
-depending on LibA.
+This interdependence of libraries, means that ABI versioning of libraries is
+more manageable at a project level, with all project libraries sharing a
+**single ABI version**. In addition, the need to maintain a stable ABI for some
+number of releases as described in the section `The DPDK ABI policy`_, means
+that ABI version increments need to carefully planned and managed at a project
+level.
-.. note::
+Major ABI versions are therefore declared every two years and are then supported
+for two years, typically aligned with the LTS release and are shared across all
+libraries. This means that a single project level ABI version, reflected in all
+individual library's soname, filename and version maps persists for two years.
- Application
- \-> LibA.old
- \-> LibB.new -> LibA.new
+.. code-block:: none
-That is a conflict which can be avoided by setting ``CONFIG_RTE_MAJOR_ABI``.
-If set, the value of ``CONFIG_RTE_MAJOR_ABI`` overwrites all - otherwise per
-library - versions defined in the libraries ``LIBABIVER``.
-An example might be ``CONFIG_RTE_MAJOR_ABI=16.11`` which will make all libraries
-``librte<?>.so.16.11`` instead of ``librte<?>.so.<LIBABIVER>``.
+ $ head ./lib/librte_acl/rte_acl_version.map
+ DPDK_20.0 {
+ global:
+ ...
+ $ head ./lib/librte_eal/rte_eal_version.map
+ DPDK_20.0 {
+ global:
+ ...
+
+When an ABI change is made between major ABI versions to a given library, a new
+section is added to that library's version map describing the impending new ABI
+version, as described in the section `Examples of ABI Macro use`_. The
+libraries soname and filename however do not change, e.g. ``libacl.so.20``, as
+ABI compatibility with the last major ABI version continues to be preserved for
+that library.
+
+.. code-block:: none
+
+ $ head ./lib/librte_acl/rte_acl_version.map
+ DPDK_20.0 {
+ global:
+ ...
+
+ DPDK_21.0 {
+ global:
+
+ } DPDK_20.0;
+ ...
+
+ $ head ./lib/librte_eal/rte_eal_version.map
+ DPDK_20.0 {
+ global:
+ ...
+
+
+However when a new ABI version is declared, for example DPDK 21.0, old
+depreciated functions may be safely removed at this point and the entire old
+major ABI version removed, see section `Deprecating an entire ABI version`_ on
+how this may be done.
+
+.. code-block:: none
+
+ $ head ./lib/librte_acl/rte_acl_version.map
+ DPDK_21.0 {
+ global:
+ ...
+
+ $ head -n 3 ./lib/librte_eal/rte_eal_version.map
+ DPDK_21.0 {
+ global:
+ ...
+
+At the same time, the major ABI version is changed atomically across all
+libraries by incrementing the major version in individual library's soname, e.g.
+``libacl.so.21``. This is done by bumping the LIBABIVER number in the libraries
+Makefile to indicate to dynamic linking applications that this is a later, and
+possibly incompatible library version:
+
+.. code-block:: c
+
+ -LIBABIVER := 20
+ +LIBABIVER := 21
-ABI versioning
---------------
Versioning Macros
~~~~~~~~~~~~~~~~~
@@ -202,7 +368,7 @@ Versioning Macros
When a symbol is exported from a library to provide an API, it also provides a
calling convention (ABI) that is embodied in its name, return type and
arguments. Occasionally that function may need to change to accommodate new
-functionality or behavior. When that occurs, it is desirable to allow for
+functionality or behavior. When that occurs, it is may be required to allow for
backward compatibility for a time with older binaries that are dynamically
linked to the DPDK.
@@ -270,16 +436,16 @@ maintain previous ABI versions that are accessible only to previously compiled
binaries
The addition of a parameter to the function is ABI breaking as the function is
-public, and existing application may use it in its current form. However, the
+public, and existing application may use it in its current form. However, the
compatibility macros in DPDK allow a developer to use symbol versioning so that
multiple functions can be mapped to the same public symbol based on when an
-application was linked to it. To see how this is done, we start with the
-requisite libraries version map file. Initially the version map file for the
-acl library looks like this
+application was linked to it. To see how this is done, we start with the
+requisite libraries version map file. Initially the version map file for the acl
+library looks like this
.. code-block:: none
- DPDK_2.0 {
+ DPDK_20.0 {
global:
rte_acl_add_rules;
@@ -305,7 +471,7 @@ This file needs to be modified as follows
.. code-block:: none
- DPDK_2.0 {
+ DPDK_20.0 {
global:
rte_acl_add_rules;
@@ -327,16 +493,16 @@ This file needs to be modified as follows
local: *;
};
- DPDK_2.1 {
+ DPDK_21.0 {
global:
rte_acl_create;
- } DPDK_2.0;
+ } DPDK_20.0;
The addition of the new block tells the linker that a new version node is
-available (DPDK_2.1), which contains the symbol rte_acl_create, and inherits the
-symbols from the DPDK_2.0 node. This list is directly translated into a list of
-exported symbols when DPDK is compiled as a shared library
+available (DPDK_21.0), which contains the symbol rte_acl_create, and inherits
+the symbols from the DPDK_20.0 node. This list is directly translated into a
+list of exported symbols when DPDK is compiled as a shared library
Next, we need to specify in the code which function map to the rte_acl_create
symbol at which versions. First, at the site of the initial symbol definition,
@@ -355,22 +521,22 @@ with the public symbol name
Note that the base name of the symbol was kept intact, as this is conducive to
the macros used for versioning symbols. That is our next step, mapping this new
-symbol name to the initial symbol name at version node 2.0. Immediately after
+symbol name to the initial symbol name at version node 20.0. Immediately after
the function, we add this line of code
.. code-block:: c
- VERSION_SYMBOL(rte_acl_create, _v20, 2.0);
+ VERSION_SYMBOL(rte_acl_create, _v20, 20.0);
Remembering to also add the rte_compat.h header to the requisite c file where
-these changes are being made. The above macro instructs the linker to create a
-new symbol ``rte_acl_create@DPDK_2.0``, which matches the symbol created in older
-builds, but now points to the above newly named function. We have now mapped
-the original rte_acl_create symbol to the original function (but with a new
-name)
+these changes are being made. The above macro instructs the linker to create a
+new symbol ``rte_acl_create@DPDK_20.0``, which matches the symbol created in
+older builds, but now points to the above newly named function. We have now
+mapped the original rte_acl_create symbol to the original function (but with a
+new name)
-Next, we need to create the 2.1 version of the symbol. We create a new function
-name, with a different suffix, and implement it appropriately
+Next, we need to create the 21.0 version of the symbol. We create a new function
+name, with a different suffix, and implement it appropriately
.. code-block:: c
@@ -384,12 +550,12 @@ name, with a different suffix, and implement it appropriately
return ctx;
}
-This code serves as our new API call. Its the same as our old call, but adds
-the new parameter in place. Next we need to map this function to the symbol
-``rte_acl_create@DPDK_2.1``. To do this, we modify the public prototype of the call
-in the header file, adding the macro there to inform all including applications,
-that on re-link, the default rte_acl_create symbol should point to this
-function. Note that we could do this by simply naming the function above
+This code serves as our new API call. Its the same as our old call, but adds the
+new parameter in place. Next we need to map this function to the symbol
+``rte_acl_create@DPDK_21.0``. To do this, we modify the public prototype of the
+call in the header file, adding the macro there to inform all including
+applications, that on re-link, the default rte_acl_create symbol should point to
+this function. Note that we could do this by simply naming the function above
rte_acl_create, and the linker would chose the most recent version tag to apply
in the version script, but we can also do this in the header file
@@ -397,11 +563,11 @@ in the version script, but we can also do this in the header file
struct rte_acl_ctx *
-rte_acl_create(const struct rte_acl_param *param);
- +rte_acl_create(const struct rte_acl_param *param, int debug);
- +BIND_DEFAULT_SYMBOL(rte_acl_create, _v21, 2.1);
+ +rte_acl_create_v21(const struct rte_acl_param *param, int debug);
+ +BIND_DEFAULT_SYMBOL(rte_acl_create, _v21, 21.0);
The BIND_DEFAULT_SYMBOL macro explicitly tells applications that include this
-header, to link to the rte_acl_create_v21 function and apply the DPDK_2.1
+header, to link to the rte_acl_create_v21 function and apply the DPDK_21.0
version node to it. This method is more explicit and flexible than just
re-implementing the exact symbol name, and allows for other features (such as
linking to the old symbol version by default, when the new ABI is to be opt-in
@@ -421,6 +587,7 @@ assumption is that the most recent version of the symbol is the one you want to
map. So, back in the C file where, immediately after ``rte_acl_create_v21`` is
defined, we add this
+
.. code-block:: c
struct rte_acl_ctx *
@@ -434,21 +601,22 @@ That tells the compiler that, when building a static library, any calls to the
symbol ``rte_acl_create`` should be linked to ``rte_acl_create_v21``
That's it, on the next shared library rebuild, there will be two versions of
-rte_acl_create, an old DPDK_2.0 version, used by previously built applications,
-and a new DPDK_2.1 version, used by future built applications.
+rte_acl_create, an old DPDK_20.0 version, used by previously built applications,
+and a new DPDK_21.0 version, used by future built applications.
Deprecating part of a public API
________________________________
-Lets assume that you've done the above update, and after a few releases have
-passed you decide you would like to retire the old version of the function.
-After having gone through the ABI deprecation announcement process, removal is
-easy. Start by removing the symbol from the requisite version map file:
+Lets assume that you've done the above update, and in preparation for the next
+major ABI version you decide you would like to retire the old version of the
+function. After having gone through the ABI deprecation announcement process,
+removal is easy. Start by removing the symbol from the requisite version map
+file:
.. code-block:: none
- DPDK_2.0 {
+ DPDK_20.0 {
global:
rte_acl_add_rules;
@@ -470,10 +638,10 @@ easy. Start by removing the symbol from the requisite version map file:
local: *;
};
- DPDK_2.1 {
+ DPDK_21.0 {
global:
rte_acl_create;
- } DPDK_2.0;
+ } DPDK_20.0;
Next remove the corresponding versioned export.
@@ -484,34 +652,26 @@ Next remove the corresponding versioned export.
Note that the internal function definition could also be removed, but its used
-in our example by the newer version _v21, so we leave it in place. This is a
-coding style choice.
-
-Lastly, we need to bump the LIBABIVER number for this library in the Makefile to
-indicate to applications doing dynamic linking that this is a later, and
-possibly incompatible library version:
-
-.. code-block:: c
-
- -LIBABIVER := 1
- +LIBABIVER := 2
+in our example by the newer version _v21, so we leave it in place and declare it
+as static. This is a coding style choice.
Deprecating an entire ABI version
_________________________________
-While removing a symbol from and ABI may be useful, it is often more practical
-to remove an entire version node at once. If a version node completely
-specifies an API, then removing part of it, typically makes it incomplete. In
-those cases it is better to remove the entire node
+While removing a symbol from an ABI may be useful, it is more practical to
+remove an entire version node at once, as is typically done at the declaration
+of a major ABI version. If a version node completely specifies an API, then
+removing part of it, typically makes it incomplete. In those cases it is better
+to remove the entire node.
To do this, start by modifying the version map file, such that all symbols from
-the node to be removed are merged into the next node in the map
+the node to be removed are merged into the next node in the map.
In the case of our map above, it would transform to look as follows
.. code-block:: none
- DPDK_2.1 {
+ DPDK_21.0 {
global:
rte_acl_add_rules;
@@ -539,8 +699,8 @@ symbols.
.. code-block:: c
- -BIND_DEFAULT_SYMBOL(rte_acl_create, _v20, 2.0);
- +BIND_DEFAULT_SYMBOL(rte_acl_create, _v21, 2.1);
+ -BIND_DEFAULT_SYMBOL(rte_acl_create, _v20, 20.0);
+ +BIND_DEFAULT_SYMBOL(rte_acl_create, _v21, 21.0);
Lastly, any VERSION_SYMBOL macros that point to the old version node should be
removed, taking care to keep, where need old code in place to support newer