``experimental``, as described in the section on :ref:`Experimental APIs
and Libraries <experimental_apis>`.
+ - In situations in which an ``experimental`` symbol has been stable for some
+ time. When promoting the symbol to become part of the next ABI version, the
+ maintainer may choose to provide an alias to the ``experimental`` tag, so
+ as not to break consuming applications.
+
#. 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``.
one release. Thereafter, the normal process of posting patch for review to
mailing list can be followed.
+After the experimental tag has been formally removed, a tree/sub-tree maintainer
+may choose to offer an alias to the experimental tag so as not to break
+applications using the symbol. The alias is then dropped at the declaration of
+next major ABI version.
+
Libraries
~~~~~~~~~
``be`` to signal that it is being used as an implementation of a particular
version of symbol ``b``.
+* ``VERSION_SYMBOL_EXPERIMENTAL(b, e)``: Creates a symbol version table entry
+ binding versioned symbol ``b@EXPERIMENTAL`` to the internal function ``be``.
+ The macro is used when a symbol matures to become part of the stable ABI, to
+ provide an alias to experimental for some time.
+
.. _example_abi_macro_usage:
Examples of ABI Macro use
enable the function version macros when building. There is no corresponding
directive required for the ``make`` build system.
+
+.. _aliasing_experimental_symbols:
+
+Aliasing experimental symbols
+_____________________________
+
+In situations in which an ``experimental`` symbol has been stable for some time,
+and it becomes a candidate for promotion to the stable ABI. At this time, when
+promoting the symbol, maintainer may choose to provide an alias to the
+``experimental`` symbol version, so as not to break consuming applications.
+
+The process to provide an alias to ``experimental`` is similar to that, of
+:ref:`symbol versioning <example_abi_macro_usage>` described above.
+Assume we have an experimental function ``rte_acl_create`` as follows:
+
+.. code-block:: c
+
+ #include <rte_compat.h>
+
+ /*
+ * Create an acl context object for apps to
+ * manipulate
+ */
+ __rte_experimental
+ struct rte_acl_ctx *
+ rte_acl_create(const struct rte_acl_param *param)
+ {
+ ...
+ }
+
+In the map file, experimental symbols are listed as part of the ``EXPERIMENTAL``
+version node.
+
+.. code-block:: none
+
+ DPDK_20 {
+ global:
+ ...
+
+ local: *;
+ };
+
+ EXPERIMENTAL {
+ global:
+
+ rte_acl_create;
+ };
+
+When we promote the symbol to the stable ABI, we simply strip the
+``__rte_experimental`` annotation from the function and move the symbol from the
+``EXPERIMENTAL`` node, to the node of the next major ABI version as follow.
+
+.. code-block:: c
+
+ /*
+ * Create an acl context object for apps to
+ * manipulate
+ */
+ struct rte_acl_ctx *
+ rte_acl_create(const struct rte_acl_param *param)
+ {
+ ...
+ }
+
+We then update the map file, adding the symbol ``rte_acl_create``
+to the ``DPDK_21`` version node.
+
+.. code-block:: none
+
+ DPDK_20 {
+ global:
+ ...
+
+ local: *;
+ };
+
+ DPDK_21 {
+ global:
+
+ rte_acl_create;
+ } DPDK_20;
+
+
+Although there are strictly no guarantees or commitments associated with
+:ref:`experimental symbols <experimental_apis>`, a maintainer may wish to offer
+an alias to experimental. The process to add an alias to experimental,
+is similar to the symbol versioning process. Assuming we have an experimental
+symbol as before, we now add the symbol to both the ``EXPERIMENTAL``
+and ``DPDK_21`` version nodes.
+
+.. code-block:: c
+
+ #include <rte_compat.h>;
+ #include <rte_function_versioning.h>
+
+ /*
+ * Create an acl context object for apps to
+ * manipulate
+ */
+ struct rte_acl_ctx *
+ rte_acl_create(const struct rte_acl_param *param)
+ {
+ ...
+ }
+
+ __rte_experimental
+ struct rte_acl_ctx *
+ rte_acl_create_e(const struct rte_acl_param *param)
+ {
+ return rte_acl_create(param);
+ }
+ VERSION_SYMBOL_EXPERIMENTAL(rte_acl_create, _e);
+
+ struct rte_acl_ctx *
+ rte_acl_create_v21(const struct rte_acl_param *param)
+ {
+ return rte_acl_create(param);
+ }
+ BIND_DEFAULT_SYMBOL(rte_acl_create, _v21, 21);
+
+In the map file, we map the symbol to both the ``EXPERIMENTAL``
+and ``DPDK_21`` version nodes.
+
+.. code-block:: none
+
+ DPDK_20 {
+ global:
+ ...
+
+ local: *;
+ };
+
+ DPDK_21 {
+ global:
+
+ rte_acl_create;
+ } DPDK_20;
+
+ EXPERIMENTAL {
+ global:
+
+ rte_acl_create;
+ };
+
+.. note::
+
+ Please note, similar to :ref:`symbol versioning <example_abi_macro_usage>`,
+ when aliasing to experimental you will also need to take care of
+ :ref:`mapping static symbols <mapping_static_symbols>`.
+
+
.. _abi_deprecation:
Deprecating part of a public API
*/
#define VERSION_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@DPDK_" RTE_STR(n))
+/*
+ * VERSION_SYMBOL_EXPERIMENTAL
+ * Creates a symbol version table entry binding the symbol <b>@EXPERIMENTAL to the internal
+ * function name <b><e>. The macro is used when a symbol matures to become part of the stable ABI,
+ * to provide an alias to experimental for some time.
+ */
+#define VERSION_SYMBOL_EXPERIMENTAL(b, e) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@EXPERIMENTAL")
+
/*
* BIND_DEFAULT_SYMBOL
* Creates a symbol version entry instructing the linker to bind references to
* No symbol versioning in use
*/
#define VERSION_SYMBOL(b, e, n)
+#define VERSION_SYMBOL_EXPERIMENTAL(b, e)
#define __vsym
#define BIND_DEFAULT_SYMBOL(b, e, n)
#define MAP_STATIC_SYMBOL(f, p) f __attribute__((alias(RTE_STR(p))))
git.droids-corp.org / dpdk.git / commitdiff