7 files changed, 420 insertions, 163 deletions

diff --git a/documentation/test-manual/history.rst b/documentation/test-manual/history.rst
deleted file mode 100644
index 89d4aad21c..0000000000
--- a/documentation/test-manual/history.rst
+++ /dev/null
@@ -1,16 +0,0 @@
-.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
-
-***********************
-Manual Revision History
-***********************
-
-.. list-table::
-   :widths: 10 15 40
-   :header-rows: 1
-
-   * - Revision
-     - Date
-     - Note
-   * - 3.2
-     - October 2020
-     - The initial document released with the Yocto Project 3.2 Release
diff --git a/documentation/test-manual/index.rst b/documentation/test-manual/index.rst
index e2198c4c39..86a2f436ea 100644
--- a/documentation/test-manual/index.rst
+++ b/documentation/test-manual/index.rst
@@ -13,6 +13,7 @@ Yocto Project Test Environment Manual
    intro
    test-process
    understand-autobuilder
-   history
+   reproducible-builds
+   yocto-project-compatible
 
 .. include:: /boilerplate.rst
diff --git a/documentation/test-manual/intro.rst b/documentation/test-manual/intro.rst
index 81c24a8c3f..c31fd11c7a 100644
--- a/documentation/test-manual/intro.rst
+++ b/documentation/test-manual/intro.rst
@@ -14,19 +14,17 @@ release works as intended. All the project's testing infrastructure and
 processes are publicly visible and available so that the community can
 see what testing is being performed, how it's being done and the current
 status of the tests and the project at any given time. It is intended
-that Other organizations can leverage off the process and testing
+that other organizations can leverage off the process and testing
 environment used by the Yocto Project to create their own automated,
 production test environment, building upon the foundations from the
 project core.
 
-Currently, the Yocto Project Test Environment Manual has no projected
-release date. This manual is a work-in-progress and is being initially
-loaded with information from the README files and notes from key
-engineers:
+This manual is a work-in-progress and is being initially loaded with
+information from the README files and notes from key engineers:
 
 -  *yocto-autobuilder2:* This
    :yocto_git:`README.md </yocto-autobuilder2/tree/README.md>`
-   is the main README which detials how to set up the Yocto Project
+   is the main README which details how to set up the Yocto Project
    Autobuilder. The ``yocto-autobuilder2`` repository represents the
    Yocto Project's console UI plugin to Buildbot and the configuration
    necessary to configure Buildbot to perform the testing the project
@@ -39,7 +37,7 @@ engineers:
    As a result, it can be used by any Continuous Improvement (CI) system
    to run builds, support getting the correct code revisions, configure
    builds and layers, run builds, and collect results. The code is
-   independent of any CI system, which means the code can work `Buildbot <https://docs.buildbot.net/0.9.15.post1/>`__,
+   independent of any CI system, which means the code can work `Buildbot <https://docs.buildbot.net/current/>`__,
    Jenkins, or others. This repository has a branch per release of the
    project defining the tests to run on a per release basis.
 
@@ -54,8 +52,8 @@ the Autobuilder tests if things work. The Autobuilder builds all test
 targets and runs all the tests.
 
 The Yocto Project uses now uses standard upstream
-`Buildbot <https://docs.buildbot.net/0.9.15.post1/>`__ (version 9) to
-drive its integration and testing. Buildbot Nine has a plug-in interface
+Buildbot (`version 3.8 <https://docs.buildbot.net/3.8.0/>`__) to
+drive its integration and testing. Buildbot has a plug-in interface
 that the Yocto Project customizes using code from the
 ``yocto-autobuilder2`` repository, adding its own console UI plugin. The
 resulting UI plug-in allows you to visualize builds in a way suited to
@@ -72,10 +70,9 @@ simple JSON files.
 .. note::
 
    The project uses Buildbot for historical reasons but also because
-   many of the project developers have knowledge of python. It is
+   many of the project developers have knowledge of Python. It is
    possible to use the outer layers from another Continuous Integration
-   (CI) system such as
-   `Jenkins <https://en.wikipedia.org/wiki/Jenkins_(software)>`__
+   (CI) system such as :wikipedia:`Jenkins <Jenkins_(software)>`
    instead of Buildbot.
 
 The following figure shows the Yocto Project Autobuilder stack with a
@@ -83,29 +80,29 @@ topology that includes a controller and a cluster of workers:
 
 .. image:: figures/ab-test-cluster.png
    :align: center
+   :width: 70%
 
-Yocto Project Tests - Types of Testing Overview
-===============================================
+Yocto Project Tests --- Types of Testing Overview
+=================================================
 
 The Autobuilder tests different elements of the project by using
-thefollowing types of tests:
+the following types of tests:
 
 -  *Build Testing:* Tests whether specific configurations build by
    varying :term:`MACHINE`,
    :term:`DISTRO`, other configuration
-   options, and the specific target images being built (or world). Used
-   to trigger builds of all the different test configurations on the
+   options, and the specific target images being built (or ``world``). This is
+   used to trigger builds of all the different test configurations on the
    Autobuilder. Builds usually cover many different targets for
    different architectures, machines, and distributions, as well as
    different configurations, such as different init systems. The
    Autobuilder tests literally hundreds of configurations and targets.
 
-   -  *Sanity Checks During the Build Process:* Tests initiated through
-      the :ref:`insane <ref-classes-insane>`
-      class. These checks ensure the output of the builds are correct.
-      For example, does the ELF architecture in the generated binaries
-      match the target system? ARM binaries would not work in a MIPS
-      system!
+   -  *Sanity Checks During the Build Process:* Tests initiated through the
+      :ref:`ref-classes-insane` class. These checks ensure the output of the
+      builds are correct. For example, does the ELF architecture in the
+      generated binaries match the target system? ARM binaries would not work
+      in a MIPS system!
 
 -  *Build Performance Testing:* Tests whether or not commonly used steps
    during builds work efficiently and avoid regressions. Tests to time
@@ -121,18 +118,19 @@ thefollowing types of tests:
 
       $ bitbake image -c testsdkext
 
-   The tests utilize the ``testsdkext`` class and the ``do_testsdkext`` task.
+   The tests use the :ref:`ref-classes-testsdk` class and the
+   ``do_testsdkext`` task.
 
 -  *Feature Testing:* Various scenario-based tests are run through the
-   :ref:`OpenEmbedded Self test (oe-selftest) <ref-manual/release-process:Testing and Quality Assurance>`. We test oe-selftest on each of the main distrubutions
+   :ref:`OpenEmbedded Self test (oe-selftest) <ref-manual/release-process:Testing and Quality Assurance>`. We test oe-selftest on each of the main distributions
    we support.
 
 -  *Image Testing:* Image tests initiated through the following command::
 
       $ bitbake image -c testimage
 
-   The tests utilize the :ref:`testimage* <ref-classes-testimage*>`
-   classes and the :ref:`ref-tasks-testimage` task.
+   The tests use the :ref:`ref-classes-testimage`
+   class and the :ref:`ref-tasks-testimage` task.
 
 -  *Layer Testing:* The Autobuilder has the possibility to test whether
    specific layers work with the test of the system. The layers tested
@@ -142,7 +140,7 @@ thefollowing types of tests:
 -  *Package Testing:* A Package Test (ptest) runs tests against packages
    built by the OpenEmbedded build system on the target machine. See the
    :ref:`Testing Packages With
-   ptest <dev-manual/common-tasks:Testing Packages With ptest>` section
+   ptest <dev-manual/packages:Testing Packages With ptest>` section
    in the Yocto Project Development Tasks Manual and the
    ":yocto_wiki:`Ptest </Ptest>`" Wiki page for more
    information on Ptest.
@@ -151,7 +149,7 @@ thefollowing types of tests:
 
       $ bitbake image -c testsdk
 
-   The tests utilize the :ref:`testsdk <ref-classes-testsdk>` class and
+   The tests use the :ref:`ref-classes-testsdk` class and
    the ``do_testsdk`` task.
 
 -  *Unit Testing:* Unit tests on various components of the system run
@@ -174,48 +172,55 @@ Tests map into the codebase as follows:
    which include the fetchers. The tests are located in
    ``bitbake/lib/*/tests``.
 
+   Some of these tests run the ``bitbake`` command, so ``bitbake/bin``
+   must be added to the ``PATH`` before running ``bitbake-selftest``.
    From within the BitBake repository, run the following::
 
-      $ bitbake-selftest
+      $ export PATH=$PWD/bin:$PATH
 
-   To skip tests that access the Internet, use the ``BB_SKIP_NETTEST``
-   variable when running "bitbake-selftest" as follows::
+   After that, you can run the selftest script::
 
-      $ BB_SKIP_NETTEST=yes bitbake-selftest
+      $ bitbake-selftest
 
    The default output is quiet and just prints a summary of what was
    run. To see more information, there is a verbose option::
 
       $ bitbake-selftest -v
 
+   To skip tests that access the Internet, use the ``BB_SKIP_NETTESTS``
+   variable when running ``bitbake-selftest`` as follows::
+
+      $ BB_SKIP_NETTESTS=yes bitbake-selftest
+
    Use this option when you wish to skip tests that access the network,
    which are mostly necessary to test the fetcher modules. To specify
    individual test modules to run, append the test module name to the
-   "bitbake-selftest" command. For example, to specify the tests for the
-   bb.data.module, run::
+   ``bitbake-selftest`` command. For example, to specify the tests for
+   ``bb.tests.data.DataExpansions``, run::
 
-      $ bitbake-selftest bb.test.data.module
+      $ bitbake-selftest bb.tests.data.DataExpansions
 
    You can also specify individual tests by defining the full name and module
    plus the class path of the test, for example::
 
-      $ bitbake-selftest bb.tests.data.TestOverrides.test_one_override
+      $ bitbake-selftest bb.tests.data.DataExpansions.test_one_var
 
-   The tests are based on `Python
-   unittest <https://docs.python.org/3/library/unittest.html>`__.
+   The tests are based on
+   `Python unittest <https://docs.python.org/3/library/unittest.html>`__.
 
 -  *oe-selftest:*
 
    -  These tests use OE to test the workflows, which include testing
       specific features, behaviors of tasks, and API unit tests.
 
-   -  The tests can take advantage of parallelism through the "-j"
+   -  The tests can take advantage of parallelism through the ``-j``
       option, which can specify a number of threads to spread the tests
       across. Note that all tests from a given class of tests will run
       in the same thread. To parallelize large numbers of tests you can
       split the class into multiple units.
 
-   -  The tests are based on Python unittest.
+   -  The tests are based on
+      `Python unittest <https://docs.python.org/3/library/unittest.html>`__.
 
    -  The code for the tests resides in
       ``meta/lib/oeqa/selftest/cases/``.
@@ -225,18 +230,18 @@ Tests map into the codebase as follows:
          $ oe-selftest -a
 
    -  To run a specific test, use the following command form where
-      testname is the name of the specific test::
+      ``testname`` is the name of the specific test::
 
          $ oe-selftest -r <testname>
 
-      For example, the following command would run the tinfoil
-      getVar API test::
+      For example, the following command would run the ``tinfoil``
+      ``getVar`` API test::
 
          $ oe-selftest -r tinfoil.TinfoilTests.test_getvar
 
       It is also possible to run a set
       of tests. For example the following command will run all of the
-      tinfoil tests::
+      ``tinfoil`` tests::
 
          $ oe-selftest -r tinfoil
 
@@ -271,7 +276,7 @@ Tests map into the codebase as follows:
    -  These tests build an extended SDK (eSDK), install that eSDK, and
       run tests against the eSDK.
 
-   -  The code for these tests resides in ``meta/lib/oeqa/esdk``.
+   -  The code for these tests resides in ``meta/lib/oeqa/sdkext/cases/``.
 
    -  To run the tests, use the following command form::
 
@@ -298,13 +303,13 @@ Tests map into the codebase as follows:
       Git repository.
 
       Use the ``oe-build-perf-report`` command to generate text reports
-      and HTML reports with graphs of the performance data. For
-      examples, see
-      :yocto_dl:`/releases/yocto/yocto-2.7/testresults/buildperf-centos7/perf-centos7.yoctoproject.org_warrior_20190414204758_0e39202.html`
+      and HTML reports with graphs of the performance data. See
+      :yocto_dl:`html </releases/yocto/yocto-4.3/testresults/buildperf-debian11/perf-debian11_nanbield_20231019191258_15b576c410.html>`
       and
-      :yocto_dl:`/releases/yocto/yocto-2.7/testresults/buildperf-centos7/perf-centos7.yoctoproject.org_warrior_20190414204758_0e39202.txt`.
+      :yocto_dl:`txt </releases/yocto/yocto-4.3/testresults/buildperf-debian11/perf-debian11_nanbield_20231019191258_15b576c410.txt>`
+      examples.
 
-   -  The tests are contained in ``lib/oeqa/buildperf/test_basic.py``.
+   -  The tests are contained in ``meta/lib/oeqa/buildperf/test_basic.py``.
 
 Test Examples
 =============
@@ -312,16 +317,14 @@ Test Examples
 This section provides example tests for each of the tests listed in the
 :ref:`test-manual/intro:How Tests Map to Areas of Code` section.
 
-For oeqa tests, testcases for each area reside in the main test
-directory at ``meta/lib/oeqa/selftest/cases`` directory.
+-  ``oe-selftest`` testcases reside in the ``meta/lib/oeqa/selftest/cases`` directory.
 
-For oe-selftest. bitbake testcases reside in the ``lib/bb/tests/``
-directory.
+-  ``bitbake-selftest`` testcases reside in the ``bitbake/lib/bb/tests/`` directory.
 
 ``bitbake-selftest``
 --------------------
 
-A simple test example from ``lib/bb/tests/data.py`` is::
+A simple test example from ``bitbake/lib/bb/tests/data.py`` is::
 
    class DataExpansions(unittest.TestCase):
       def setUp(self):
@@ -334,21 +337,24 @@ A simple test example from ``lib/bb/tests/data.py`` is::
             val = self.d.expand("${foo}")
             self.assertEqual(str(val), "value_of_foo")
 
-In this example, a ``DataExpansions`` class of tests is created,
-derived from standard python unittest. The class has a common ``setUp``
-function which is shared by all the tests in the class. A simple test is
-then added to test that when a variable is expanded, the correct value
-is found.
+In this example, a ``DataExpansions`` class of tests is created, derived from
+standard `Python unittest <https://docs.python.org/3/library/unittest.html>`__.
+The class has a common ``setUp`` function which is shared by all the tests in
+the class. A simple test is then added to test that when a variable is
+expanded, the correct value is found.
 
-Bitbake selftests are straightforward python unittest. Refer to the
-Python unittest documentation for additional information on writing
-these tests at: https://docs.python.org/3/library/unittest.html.
+BitBake selftests are straightforward
+`Python unittest <https://docs.python.org/3/library/unittest.html>`__.
+Refer to the `Python unittest documentation
+<https://docs.python.org/3/library/unittest.html>`__ for additional information
+on writing such tests.
 
 ``oe-selftest``
 ---------------
 
 These tests are more complex due to the setup required behind the scenes
-for full builds. Rather than directly using Python's unittest, the code
+for full builds. Rather than directly using `Python unittest
+<https://docs.python.org/3/library/unittest.html>`__, the code
 wraps most of the standard objects. The tests can be simple, such as
 testing a command from within the OE build environment using the
 following example::
@@ -385,14 +391,14 @@ so tests within a given test class should always run in the same build,
 while tests in different classes or modules may be split into different
 builds. There is no data store available for these tests since the tests
 launch the ``bitbake`` command and exist outside of its context. As a
-result, common bitbake library functions (bb.\*) are also unavailable.
+result, common BitBake library functions (``bb.\*``) are also unavailable.
 
 ``testimage``
 -------------
 
 These tests are run once an image is up and running, either on target
 hardware or under QEMU. As a result, they are assumed to be running in a
-target image environment, as opposed to a host build environment. A
+target image environment, as opposed to in a host build environment. A
 simple example from ``meta/lib/oeqa/runtime/cases/python.py`` contains
 the following::
 
@@ -407,19 +413,19 @@ the following::
 
 In this example, the ``OERuntimeTestCase`` class wraps
 ``unittest.TestCase``. Within the test, ``self.target`` represents the
-target system, where commands can be run on it using the ``run()``
+target system, where commands can be run using the ``run()``
 method.
 
-To ensure certain test or package dependencies are met, you can use the
+To ensure certain tests or package dependencies are met, you can use the
 ``OETestDepends`` and ``OEHasPackage`` decorators. For example, the test
-in this example would only make sense if python3-core is installed in
+in this example would only make sense if ``python3-core`` is installed in
 the image.
 
 ``testsdk_ext``
 ---------------
 
 These tests are run against built extensible SDKs (eSDKs). The tests can
-assume that the eSDK environment has already been setup. An example from
+assume that the eSDK environment has already been set up. An example from
 ``meta/lib/oeqa/sdk/cases/devtool.py`` contains the following::
 
    class DevtoolTest(OESDKExtTestCase):
@@ -466,15 +472,15 @@ following::
             output = self._run(cmd)
             self.assertEqual(output, "Hello, world\n")
 
-In this example, if nativesdk-python3-core has been installed into the SDK, the code runs
-the python3 interpreter with a basic command to check it is working
-correctly. The test would only run if python3 is installed in the SDK.
+In this example, if ``nativesdk-python3-core`` has been installed into the SDK,
+the code runs the ``python3`` interpreter with a basic command to check it is
+working correctly. The test would only run if Python3 is installed in the SDK.
 
 ``oe-build-perf-test``
 ----------------------
 
 The performance tests usually measure how long operations take and the
-resource utilisation as that happens. An example from
+resource utilization as that happens. An example from
 ``meta/lib/oeqa/buildperf/test_basic.py`` contains the following::
 
    class Test3(BuildPerfTestCase):
@@ -506,15 +512,15 @@ workers, consider the following:
 
 **Running "cleanall" is not permitted.**
 
-This can delete files from DL_DIR which would potentially break other
-builds running in parallel. If this is required, DL_DIR must be set to
+This can delete files from :term:`DL_DIR` which would potentially break other
+builds running in parallel. If this is required, :term:`DL_DIR` must be set to
 an isolated directory.
 
 **Running "cleansstate" is not permitted.**
 
-This can delete files from SSTATE_DIR which would potentially break
-other builds running in parallel. If this is required, SSTATE_DIR must
-be set to an isolated directory. Alternatively, you can use the "-f"
+This can delete files from :term:`SSTATE_DIR` which would potentially break
+other builds running in parallel. If this is required, :term:`SSTATE_DIR` must
+be set to an isolated directory. Alternatively, you can use the ``-f``
 option with the ``bitbake`` command to "taint" tasks by changing the
 sstate checksums to ensure sstate cache items will not be reused.
 
@@ -524,5 +530,5 @@ This is particularly true for oe-selftests since these can run in
 parallel and changing metadata leads to changing checksums, which
 confuses BitBake while running in parallel. If this is necessary, copy
 layers to a temporary location and modify them. Some tests need to
-change metadata, such as the devtool tests. To prevent the metadate from
+change metadata, such as the devtool tests. To protect the metadata from
 changes, set up temporary copies of that data first.
diff --git a/documentation/test-manual/reproducible-builds.rst b/documentation/test-manual/reproducible-builds.rst
new file mode 100644
index 0000000000..91f94a5c74
--- /dev/null
+++ b/documentation/test-manual/reproducible-builds.rst
@@ -0,0 +1,137 @@
+.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
+
+*******************
+Reproducible Builds
+*******************
+
+================
+How we define it
+================
+
+The Yocto Project defines reproducibility as where a given input build
+configuration will give the same binary output regardless of when it is built
+(now or in 5 years time), regardless of the path on the filesystem the build is
+run in, and regardless of the distro and tools on the underlying host system the
+build is running on.
+
+==============
+Why it matters
+==============
+
+The project aligns with the `Reproducible Builds project
+<https://reproducible-builds.org/>`__, which shares information about why
+reproducibility matters. The primary focus of the project is the ability to
+detect security issues being introduced. However, from a Yocto Project
+perspective, it is also hugely important that our builds are deterministic. When
+you build a given input set of metadata, we expect you to get consistent output.
+This has always been a key focus but, :ref:`since release 3.1 ("dunfell")
+<migration-guides/migration-3.1:reproducible builds now enabled by default>`,
+it is now true down to the binary level including timestamps.
+
+For example, at some point in the future life of a product, you find that you
+need to rebuild to add a security fix. If this happens, only the components that
+have been modified should change at the binary level. This would lead to much
+easier and clearer bounds on where validation is needed.
+
+This also gives an additional benefit to the project builds themselves, our
+:ref:`overview-manual/concepts:Hash Equivalence` for
+:ref:`overview-manual/concepts:Shared State` object reuse works much more
+effectively when the binary output remains the same.
+
+.. note::
+
+   We strongly advise you to make sure your project builds reproducibly
+   before finalizing your production images. It would be too late if you
+   only address this issue when the first updates are required.
+
+===================
+How we implement it
+===================
+
+There are many different aspects to build reproducibility, but some particular
+things we do within the build system to ensure reproducibility include:
+
+-  Adding mappings to the compiler options to ensure debug filepaths are mapped
+   to consistent target compatible paths. This is done through the
+   :term:`DEBUG_PREFIX_MAP` variable which sets the ``-fmacro-prefix-map`` and
+   ``-fdebug-prefix-map`` compiler options correctly to map to target paths.
+-  Being explicit about recipe dependencies and their configuration (no floating
+   configure options or host dependencies creeping in). In particular this means
+   making sure :term:`PACKAGECONFIG` coverage covers configure options which may
+   otherwise try and auto-detect host dependencies.
+-  Using recipe specific sysroots to isolate recipes so they only see their
+   dependencies. These are visible as ``recipe-sysroot`` and
+   ``recipe-sysroot-native`` directories within the :term:`WORKDIR` of a given
+   recipe and are populated only with the dependencies a recipe has.
+-  Build images from a reduced package set: only packages from recipes the image
+   depends upon.
+-  Filtering the tools available from the host's ``PATH`` to only a specific set
+   of tools, set using the :term:`HOSTTOOLS` variable.
+
+=========================================
+Can we prove the project is reproducible?
+=========================================
+
+Yes, we can prove it and we regularly test this on the Autobuilder. At the
+time of writing (release 3.3, "hardknott"), :term:`OpenEmbedded-Core (OE-Core)`
+is 100% reproducible for all its recipes (i.e. world builds) apart from the Go
+language and Ruby documentation packages. Unfortunately, the current
+implementation of the Go language has fundamental reproducibility problems as
+it always depends upon the paths it is built in.
+
+.. note::
+
+   Only BitBake and :term:`OpenEmbedded-Core (OE-Core)`, which is the ``meta``
+   layer in Poky, guarantee complete reproducibility. The moment you add
+   another layer, this warranty is voided, because of additional configuration
+   files, ``bbappend`` files, overridden classes, etc.
+
+To run our automated selftest, as we use in our CI on the Autobuilder, you can
+run::
+
+   oe-selftest -r reproducible.ReproducibleTests.test_reproducible_builds
+
+This defaults to including a ``world`` build so, if other layers are added, it would
+also run the tests for recipes in the additional layers. Different build targets
+can be defined using the :term:`OEQA_REPRODUCIBLE_TEST_TARGET` variable in ``local.conf``.
+The first build will be run using :ref:`Shared State <overview-manual/concepts:Shared State>` if
+available, the second build explicitly disables
+:ref:`Shared State <overview-manual/concepts:Shared State>` except for recipes defined in
+the :term:`OEQA_REPRODUCIBLE_TEST_SSTATE_TARGETS` variable, and builds on the
+specific host the build is running on. This means we can test reproducibility
+builds between different host distributions over time on the Autobuilder.
+
+If ``OEQA_DEBUGGING_SAVED_OUTPUT`` is set, any differing packages will be saved
+here. The test is also able to run the ``diffoscope`` command on the output to
+generate HTML files showing the differences between the packages, to aid
+debugging. On the Autobuilder, these appear under
+https://autobuilder.yocto.io/pub/repro-fail/ in the form ``oe-reproducible +
+<date> + <random ID>``, e.g. ``oe-reproducible-20200202-1lm8o1th``.
+
+The project's current reproducibility status can be seen at
+:yocto_home:`/reproducible-build-results/`
+
+You can also check the reproducibility status on supported host distributions:
+
+-  CentOS: :yocto_ab:`/typhoon/#/builders/reproducible-centos`
+-  Debian: :yocto_ab:`/typhoon/#/builders/reproducible-debian`
+-  Fedora: :yocto_ab:`/typhoon/#/builders/reproducible-fedora`
+-  Ubuntu: :yocto_ab:`/typhoon/#/builders/reproducible-ubuntu`
+
+===============================
+Can I test my layer or recipes?
+===============================
+
+Once again, you can run a ``world`` test using the
+:ref:`oe-selftest <ref-manual/release-process:Testing and Quality Assurance>`
+command provided above. This functionality is implemented
+in :oe_git:`meta/lib/oeqa/selftest/cases/reproducible.py
+</openembedded-core/tree/meta/lib/oeqa/selftest/cases/reproducible.py>`.
+
+You could subclass the test and change ``targets`` to a different target.
+
+You may also change ``sstate_targets`` which would allow you to "pre-cache" some
+set of recipes before the test, meaning they are excluded from reproducibility
+testing. As a practical example, you could set ``sstate_targets`` to
+``core-image-sato``, then setting ``targets`` to ``core-image-sato-sdk`` would
+run reproducibility tests only on the targets belonging only to ``core-image-sato-sdk``.
diff --git a/documentation/test-manual/test-process.rst b/documentation/test-manual/test-process.rst
index 8a5e29d922..7bec5ba828 100644
--- a/documentation/test-manual/test-process.rst
+++ b/documentation/test-manual/test-process.rst
@@ -20,8 +20,8 @@ helps review and test patches and this is his testing tree).
 We have two broad categories of test builds, including "full" and
 "quick". On the Autobuilder, these can be seen as "a-quick" and
 "a-full", simply for ease of sorting in the UI. Use our Autobuilder
-console view to see where me manage most test-related items, available
-at: :yocto_ab:`/typhoon/#/console`.
+:yocto_ab:`console view </typhoon/#/console>` to see where we manage most
+test-related items.
 
 Builds are triggered manually when the test branches are ready. The
 builds are monitored by the SWAT team. For additional information, see
@@ -34,24 +34,21 @@ which the result was required.
 
 The Autobuilder does build the ``master`` branch once daily for several
 reasons, in particular, to ensure the current ``master`` branch does
-build, but also to keep ``yocto-testresults``
-(:yocto_git:`/yocto-testresults/`),
-buildhistory
-(:yocto_git:`/poky-buildhistory/`), and
-our sstate up to date. On the weekend, there is a master-next build
+build, but also to keep (:yocto_git:`yocto-testresults </yocto-testresults/>`),
+(:yocto_git:`buildhistory </poky-buildhistory/>`), and
+our sstate up to date. On the weekend, there is a ``master-next`` build
 instead to ensure the test results are updated for the less frequently
 run targets.
 
-Performance builds (buildperf-\* targets in the console) are triggered
+Performance builds (``buildperf-\*`` targets in the console) are triggered
 separately every six hours and automatically push their results to the
-buildstats repository at:
-:yocto_git:`/yocto-buildstats/`.
+:yocto_git:`buildstats </yocto-buildstats/>` repository.
 
-The 'quick' targets have been selected to be the ones which catch the
-most failures or give the most valuable data. We run 'fast' ptests in
+The "quick" targets have been selected to be the ones which catch the
+most failures or give the most valuable data. We run "fast" ptests in
 this case for example but not the ones which take a long time. The quick
-target doesn't include \*-lsb builds for all architectures, some world
-builds and doesn't trigger performance tests or ltp testing. The full
+target doesn't include ``\*-lsb`` builds for all architectures, some ``world``
+builds and doesn't trigger performance tests or ``ltp`` testing. The full
 build includes all these things and is slower but more comprehensive.
 
 Release Builds
@@ -59,20 +56,20 @@ Release Builds
 
 The project typically has two major releases a year with a six month
 cadence in April and October. Between these there would be a number of
-milestone releases (usually four) with the final one being stablization
+milestone releases (usually four) with the final one being stabilization
 only along with point releases of our stable branches.
 
 The build and release process for these project releases is similar to
-that in `Day to Day Development <#test-daily-devel>`__, in that the
+that in :ref:`test-manual/test-process:day to day development`, in that the
 a-full target of the Autobuilder is used but in addition the form is
-configured to generate and publish artefacts and the milestone number,
+configured to generate and publish artifacts and the milestone number,
 version, release candidate number and other information is entered. The
-box to "generate an email to QA"is also checked.
+box to "generate an email to QA" is also checked.
 
-When the build completes, an email is sent out using the send-qa-email
-script in the ``yocto-autobuilder-helper`` repository to the list of
-people configured for that release. Release builds are placed into a
-directory in https://autobuilder.yocto.io/pub/releases on the
+When the build completes, an email is sent out using the ``send-qa-email``
+script in the :yocto_git:`yocto-autobuilder-helper </yocto-autobuilder-helper>`
+repository to the list of people configured for that release. Release builds
+are placed into a directory in https://autobuilder.yocto.io/pub/releases on the
 Autobuilder which is included in the email. The process from here is
 more manual and control is effectively passed to release engineering.
 The next steps include:
@@ -80,14 +77,15 @@ The next steps include:
 -  QA teams respond to the email saying which tests they plan to run and
    when the results will be available.
 
--  QA teams run their tests and share their results in the yocto-
-   testresults-contrib repository, along with a summary of their
-   findings.
+-  QA teams run their tests and share their results in the
+   :yocto_git:`yocto-testresults-contrib </yocto-testresults-contrib>`
+   repository, along with a summary of their findings.
 
 -  Release engineering prepare the release as per their process.
 
 -  Test results from the QA teams are included into the release in
-   separate directories and also uploaded to the yocto-testresults
+   separate directories and also uploaded to the
+   :yocto_git:`yocto-testresults </yocto-testresults>`
    repository alongside the other test results for the given revision.
 
 -  The QA report in the final release is regenerated using resulttool to
diff --git a/documentation/test-manual/understand-autobuilder.rst b/documentation/test-manual/understand-autobuilder.rst
index 199cc97a85..6b4fab4f0b 100644
--- a/documentation/test-manual/understand-autobuilder.rst
+++ b/documentation/test-manual/understand-autobuilder.rst
@@ -9,31 +9,31 @@ Execution Flow within the Autobuilder
 
 The "a-full" and "a-quick" targets are the usual entry points into the
 Autobuilder and it makes sense to follow the process through the system
-starting there. This is best visualised from the Autobuilder Console
-view (:yocto_ab:`/typhoon/#/console`).
+starting there. This is best visualized from the :yocto_ab:`Autobuilder
+Console view </typhoon/#/console>`.
 
 Each item along the top of that view represents some "target build" and
 these targets are all run in parallel. The 'full' build will trigger the
 majority of them, the "quick" build will trigger some subset of them.
 The Autobuilder effectively runs whichever configuration is defined for
-each of those targets on a seperate buildbot worker. To understand the
+each of those targets on a separate buildbot worker. To understand the
 configuration, you need to look at the entry on ``config.json`` file
-within the ``yocto-autobuilder-helper`` repository. The targets are
-defined in the ‘overrides' section, a quick example could be qemux86-64
-which looks like::
+within the :yocto_git:`yocto-autobuilder-helper </yocto-autobuilder-helper>`
+repository. The targets are defined in the ``overrides`` section, a quick
+example could be ``qemux86-64`` which looks like::
 
    "qemux86-64" : {
          "MACHINE" : "qemux86-64",
          "TEMPLATE" : "arch-qemu",
          "step1" : {
                "extravars" : [
-                     "IMAGE_FSTYPES_append = ' wic wic.bmap'"
+                     "IMAGE_FSTYPES:append = ' wic wic.bmap'"
                     ]
         }
    },
 
-And to expand that, you need the "arch-qemu" entry from
-the "templates" section, which looks like::
+And to expand that, you need the ``arch-qemu`` entry from
+the ``templates`` section, which looks like::
 
    "arch-qemu" : {
          "BUILDINFO" : true,
@@ -54,20 +54,20 @@ the "templates" section, which looks like::
          }
    },
 
-Combining these two entries you can see that "qemux86-64" is a three step build where the
-``bitbake BBTARGETS`` would be run, then ``bitbake SANITYTARGETS`` for each step; all for
-``MACHINE="qemx86-64"`` but with differing SDKMACHINE settings. In step
-1 an extra variable is added to the ``auto.conf`` file to enable wic
-image generation.
+Combining these two entries you can see that ``qemux86-64`` is a three step
+build where ``bitbake BBTARGETS`` would be run, then ``bitbake SANITYTARGETS``
+for each step; all for ``MACHINE="qemux86-64"`` but with differing
+:term:`SDKMACHINE` settings. In step 1, an extra variable is added to the
+``auto.conf`` file to enable wic image generation.
 
 While not every detail of this is covered here, you can see how the
 template mechanism allows quite complex configurations to be built up
 yet allows duplication and repetition to be kept to a minimum.
 
-The different build targets are designed to allow for parallelisation,
+The different build targets are designed to allow for parallelization,
 so different machines are usually built in parallel, operations using
 the same machine and metadata are built sequentially, with the aim of
-trying to optimise build efficiency as much as possible.
+trying to optimize build efficiency as much as possible.
 
 The ``config.json`` file is processed by the scripts in the Helper
 repository in the ``scripts`` directory. The following section details
@@ -88,9 +88,9 @@ roughly consist of:
 
 #. *Obtain yocto-autobuilder-helper*
 
-   This step clones the ``yocto-autobuilder-helper`` git repository.
-   This is necessary to prevent the requirement to maintain all the
-   release or project-specific code within Buildbot. The branch chosen
+   This step clones the :yocto_git:`yocto-autobuilder-helper </yocto-autobuilder-helper>`
+   git repository. This is necessary to avoid the requirement to maintain all
+   the release or project-specific code within Buildbot. The branch chosen
    matches the release being built so we can support older releases and
    still make changes in newer ones.
 
@@ -111,7 +111,7 @@ roughly consist of:
    :ref:`test-manual/understand-autobuilder:Autobuilder Clone Cache`.
 
    This step has two possible modes of operation. If the build is part
-   of a parent build, its possible that all the repositories needed may
+   of a parent build, it's possible that all the repositories needed may
    already be available, ready in a pre-prepared directory. An "a-quick"
    or "a-full" build would prepare this before starting the other
    sub-target builds. This is done for two reasons:
@@ -130,7 +130,7 @@ roughly consist of:
 
 #. *Call scripts/run-config*
 
-   This is another call into the Helper scripts where its expected that
+   This is another call into the Helper scripts where it's expected that
    the main functionality of this target will be executed.
 
 Autobuilder Technology
@@ -163,16 +163,17 @@ Autobuilder Worker Janitor
 --------------------------
 
 This is a process running on each Worker that performs two basic
-operations, including background file deletion at IO idle (see :ref:`test-manual/understand-autobuilder:Autobuilder Target Execution Overview`: Run clobberdir) and
-maintainenance of a cache of cloned repositories to improve the speed
+operations, including background file deletion at IO idle (see
+"Run clobberdir" in :ref:`test-manual/understand-autobuilder:Autobuilder Target Execution Overview`)
+and maintenance of a cache of cloned repositories to improve the speed
 the system can checkout repositories.
 
 Shared DL_DIR
 -------------
 
-The Workers are all connected over NFS which allows DL_DIR to be shared
+The Workers are all connected over NFS which allows :term:`DL_DIR` to be shared
 between them. This reduces network accesses from the system and allows
-the build to be sped up. Usage of the directory within the build system
+the build to be sped up. The usage of the directory within the build system
 is designed to be able to be shared over NFS.
 
 Shared SSTATE_DIR
@@ -180,8 +181,8 @@ Shared SSTATE_DIR
 
 The Workers are all connected over NFS which allows the ``sstate``
 directory to be shared between them. This means once a Worker has built
-an artifact, all the others can benefit from it. Usage of the directory
-within the directory is designed for sharing over NFS.
+an artifact, all the others can benefit from it. The usage of the directory
+within the build system is designed for sharing over NFS.
 
 Resulttool
 ----------
@@ -192,7 +193,7 @@ in a given build and their status. Additional information, such as
 failure logs or the time taken to run the tests, may also be included.
 
 Resulttool is part of OpenEmbedded-Core and is used to manipulate these
-json results files. It has the ability to merge files together, display
+JSON results files. It has the ability to merge files together, display
 reports of the test results and compare different result files.
 
 For details, see :yocto_wiki:`/Resulttool`.
@@ -204,9 +205,9 @@ The ``scripts/run-config`` execution is where most of the work within
 the Autobuilder happens. It runs through a number of steps; the first
 are general setup steps that are run once and include:
 
-#. Set up any ``buildtools-tarball`` if configured.
+#. Set up any :term:`buildtools` tarball if configured.
 
-#. Call "buildhistory-init" if buildhistory is configured.
+#. Call ``buildhistory-init`` if :ref:`ref-classes-buildhistory` is configured.
 
 For each step that is configured in ``config.json``, it will perform the
 following:
@@ -242,7 +243,7 @@ of post-build steps, including:
 #. Call ``scripts/upload-error-reports`` to send any error reports
    generated to the remote server.
 
-#. Cleanup the build directory using
+#. Cleanup the :term:`Build Directory` using
    :ref:`test-manual/understand-autobuilder:clobberdir` if the build was successful,
    else rename it to "build-renamed" for potential future debugging.
 
@@ -250,15 +251,16 @@ Deploying Yocto Autobuilder
 ===========================
 
 The most up to date information about how to setup and deploy your own
-Autbuilder can be found in README.md in the ``yocto-autobuilder2``
-repository.
+Autobuilder can be found in :yocto_git:`README.md </yocto-autobuilder2/tree/README.md>`
+in the :yocto_git:`yocto-autobuilder2 </yocto-autobuilder2>` repository.
 
-We hope that people can use the ``yocto-autobuilder2`` code directly but
-it is inevitable that users will end up needing to heavily customise the
-``yocto-autobuilder-helper`` repository, particularly the
-``config.json`` file as they will want to define their own test matrix.
+We hope that people can use the :yocto_git:`yocto-autobuilder2 </yocto-autobuilder2>`
+code directly but it is inevitable that users will end up needing to heavily
+customize the :yocto_git:`yocto-autobuilder-helper </yocto-autobuilder-helper>`
+repository, particularly the ``config.json`` file as they will want to define
+their own test matrix.
 
-The Autobuilder supports wo customization options:
+The Autobuilder supports two customization options:
 
 -  variable substitution
 
@@ -278,7 +280,7 @@ environment::
    $ ABHELPER_JSON="config.json /some/location/local.json"
 
 One issue users often run into is validation of the ``config.json`` files. A
-tip for minimizing issues from invalid json files is to use a Git
+tip for minimizing issues from invalid JSON files is to use a Git
 ``pre-commit-hook.sh`` script to verify the JSON file before committing
 it. Create a symbolic link as follows::
 
diff --git a/documentation/test-manual/yocto-project-compatible.rst b/documentation/test-manual/yocto-project-compatible.rst
new file mode 100644
index 0000000000..65d924fad9
--- /dev/null
+++ b/documentation/test-manual/yocto-project-compatible.rst
@@ -0,0 +1,129 @@
+.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
+
+************************
+Yocto Project Compatible
+************************
+
+============
+Introduction
+============
+
+After the introduction of layers to OpenEmbedded, it quickly became clear
+that while some layers were popular and worked well, others developed a
+reputation for being "problematic". Those were layers which didn't
+interoperate well with others and tended to assume they controlled all
+the aspects of the final output.  This usually isn't intentional but happens
+because such layers are often created by developers with a particular focus
+(e.g. a company's :term:`BSP<Board Support Package (BSP)>`) whilst the end
+users have a different one (e.g. integrating that
+:term:`BSP<Board Support Package (BSP)>` into a product).
+
+As a result of noticing such patterns and friction between layers, the project
+developed the "Yocto Project Compatible" badge program, allowing layers
+following the best known practises to be marked as being widely compatible
+with other ones. This takes the form of a set of "yes/no" binary answer
+questions where layers can declare if they meet the appropriate criteria.
+In the second version of the program, a script was added to make validation
+easier and clearer, the script is called  ``yocto-check-layer`` and is
+available in :term:`OpenEmbedded-Core (OE-Core)`.
+
+See :ref:`dev-manual/layers:making sure your layer is compatible with yocto project`
+for details.
+
+========
+Benefits
+========
+
+:ref:`overview-manual/yp-intro:the yocto project layer model` is powerful
+and flexible: it gives users the ultimate power to change pretty much any
+aspect of the system but as with most things, power comes with responsibility.
+The Yocto Project would like to see people able to mix and match BSPs with
+distro configs or software stacks and be able to merge succesfully.
+Over time, the project identified characteristics in layers that allow them
+to operate well together. "anti-patterns" were also found, preventing layers
+from working well together.
+
+The intent of the compatibility program is simple: if the layer passes the
+compatibility tests, it is considered "well behaved" and should operate
+and cooperate well with other compatible layers.
+
+The benefits of compatibility can be seen from multiple different user and
+member perspectives. From a hardware perspective
+(a :ref:`overview-manual/concepts:bsp layer`), compatibility means the
+hardware can be used in many different products and use cases without
+impacting the software stacks being run with it. For a company developing
+a product, compatibility gives you a specification / standard you can
+require in a contract and then know it will have certain desired
+characteristics for interoperability. It also puts constraints on how invasive
+the code bases are into the rest of the system, meaning that multiple
+different separate hardware support layers can coexist (e.g. for multiple
+product lines from different hardware manufacturers). This can also make it
+easier for one or more parties to upgrade those system components for security
+purposes during the lifecycle of a product.
+
+==================
+Validating a layer
+==================
+
+The badges are available to members of the Yocto Project (as member benefit)
+and to open source projects run on a non-commercial basis. However, anyone can
+answer the questions and run the script.
+
+The project encourages all layer maintainers to review the questions and the
+output from the script against their layer, as the way some layers are
+constructed often has unintended consequences. The questions and the script
+are designed to highlight known issues which are often easy to solve. This
+makes layers easier to use and therefore more popular.
+
+It is intended that over time, the tests will evolve as new best known
+practices are identified, and as new interoperability issues are found,
+unnecessarily restricting layer interoperability. If anyone becomes aware of
+either type, please let the project know through the
+:yocto_home:`technical calls </public-virtual-meetings/>`,
+the :yocto_home:`mailing lists </community/mailing-lists/>`
+or through the :oe_wiki:`Technical Steering Committee (TSC) </TSC>`.
+The TSC is responsible for the technical criteria used by the program.
+
+Layers are divided into three types:
+
+-  :ref:`"BSP" or "hardware support"<overview-manual/concepts:bsp layer>`
+   layers contain support for particular pieces of hardware. This includes
+   kernel and boot loader configuration, and any recipes for firmware or
+   kernel modules needed for the hardware. Such layers usually correspond
+   to a :term:`MACHINE` setting.
+
+-  :ref:`"distro" layers<overview-manual/concepts:distro layer>` defined
+   as layers providing configuration options and settings such as the
+   choice of init system, compiler and optimisation options, and
+   configuration and choices of software components. This would usually
+   correspond to a :term:`DISTRO` setting.
+
+-  "software" layers are usually recipes. A layer might target a
+   particular graphical UI or software stack component.
+
+Here are key best practices the program tries to encourage:
+
+-  A layer should clearly show who maintains it, and who change
+   submissions and bug reports should be sent to.
+
+-  Where multiple types of functionality are present, the layer should
+   be internally divided into sublayers to separate these components.
+   That's because some users may only need one of them and separability
+   is a key best practice.
+
+-  Adding a layer to a build should not modify that build, unless the
+   user changes a configuration setting to activate the layer, by selecting
+   a :term:`MACHINE`, a :term:`DISTRO` or a :term:`DISTRO_FEATURES` setting.
+
+-  Layers should be documenting where they don’t support normal "core"
+   functionality such as where debug symbols are disabled or missing, where
+   development headers and on-target library usage may not work or where
+   functionality like the SDK/eSDK would not be expected to work.
+
+The project does test the compatibility status of the core project layers on
+its :doc:`Autobuilder </test-manual/understand-autobuilder>`.
+
+The official form to submit compatibility requests with is at
+:yocto_home:`/ecosystem/branding/compatible-registration/`.
+Applicants can display the badge they get when their application is successful.
+