[dpdk-dev] [PATCH v3] doc: add section describing new abi versions

[Ray Kinsella <mdr@ashroe.eu>]

Added a section describing new abi versions, this provides pointers to
the relevant amended rules that apply during the abi breakage window.
Also remove the large note a the head of the abi policy describing the
abi stability process that has taken place over the previous year.

Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
---
V3: Added the patch version.
V2: Updated to add removing aliases to experimental.
---
 doc/guides/contributing/abi_policy.rst     | 40 ++++++++++++++++++++++++------
 doc/guides/contributing/abi_versioning.rst |  6 ++---
 2 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/doc/guides/contributing/abi_policy.rst b/doc/guides/contributing/abi_policy.rst
index ab9daf5..31d250a 100644
--- a/doc/guides/contributing/abi_policy.rst
+++ b/doc/guides/contributing/abi_policy.rst
@@ -14,8 +14,8 @@ General Guidelines
 ------------------

 #. Major ABI versions are declared no more frequently than yearly. Compatibility
-   with the major ABI version is mandatory in subsequent releases until a new
-   major ABI version is declared.
+   with the major ABI version is mandatory in subsequent releases until a
+   :ref:`new major ABI version <new_abi_version>` is declared.
 #. Major ABI versions are usually but not always declared aligned with a
    :ref:`LTS release <stable_lts_releases>`.
 #. The ABI version is managed at a project level in DPDK, and is reflected in
@@ -35,12 +35,6 @@ General Guidelines

 .. note::

-   In 2019, the DPDK community stated its intention to move to ABI stable
-   releases, over a number of release cycles. This change begins with
-   maintaining ABI stability through one year of DPDK releases starting from
-   DPDK 19.11. This policy will be reviewed in 2020, with intention of
-   lengthening the stability period. Additional implementation detail can be
-   found in the :ref:`release notes <20_02_abi_changes>`.
    Please note that this policy does not currently apply to the
    :doc:`Windows build <../windows_gsg/intro>`.

@@ -288,11 +282,41 @@ added to the Release Notes:
   these changes. Binaries using this library built prior to ABI version 21 will
   require updating and recompilation.

+
+.. _new_abi_version:
+
+New ABI versions
+------------------
+
+A new ABI version may be declared aligned with a given release. The requirement
+to preserve compatibility with the previous major ABI version is then dropped
+for the duration of this release cycle. This is commonly known as the *ABI
+breakage window*, and some amended rules apply during this cycle:
+
+ * The requirement to preserve compatibility with the previous major ABI
+   version, as described in the section :ref:`abi_changes` does not apply.
+ * Contributors of compatibility preserving code in previous releases, are now
+   required to remove this compatibility code, as described in the section
+   :ref:`abi_changes`.
+ * Symbol versioning references to the old ABI version are updated to reference
+   the new ABI version, as described in the section.
+   :ref:`deprecating_entire_abi`.
+ * Contributors of aliases to experimental in previous releases, as described in
+   section :ref:`aliasing_experimental_symbols`, are now required to remove
+   these aliases.
+ * Finally, the *ABI breakage window* is *not* permission to circumvent the
+   other aspects of the procedures to make ABI changes described in
+   :ref:`abi_changes`, that is, 3 ACKs of the requirement to break the ABI and
+   the observance of a deprecation notice are still considered mandatory.
+
 .. _experimental_apis:

 Experimental
 ------------

+Major ABI versions are usually but not always declared aligned with a
+:ref:`LTS release <stable_lts_releases>`.
+
 APIs
 ~~~~

diff --git a/doc/guides/contributing/abi_versioning.rst b/doc/guides/contributing/abi_versioning.rst
index b1d09c7..3d35b1a 100644
--- a/doc/guides/contributing/abi_versioning.rst
+++ b/doc/guides/contributing/abi_versioning.rst
@@ -673,9 +673,9 @@ symbols.
  -BIND_DEFAULT_SYMBOL(rte_acl_create, _v20, 20);
  +BIND_DEFAULT_SYMBOL(rte_acl_create, _v21, 21);

-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
-versions of the symbol.
+Lastly, any VERSION_SYMBOL macros that point to the old version nodes should be
+removed, taking care to preserve any code that is shared with the new version
+node.


 Running the ABI Validator
--
2.7.4