Another point to mention is that UPSTREAM_* variables do not need to be set, most of the time. They are only required when upstream does something unusual, and defaults do not work.

Alex

On Wed, 15 Sept 2021 at 19:58, Michael Opdenacker <michael.opdenacker@bootlin.com> wrote:
- Mention "devtool latest-version recipe" to process a single version
- Explain that the mechanism is controlled by the UPSTREAM_CHECK*
  variables, which are not referred to anywhere else in the manuals,
  except in the variable index.

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
---
 .../ref-manual/devtool-reference.rst          | 29 +++++++++++++------
 documentation/ref-manual/variables.rst        |  4 +--
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/documentation/ref-manual/devtool-reference.rst b/documentation/ref-manual/devtool-reference.rst
index 5fd51569a3..2cf9fd43a3 100644
--- a/documentation/ref-manual/devtool-reference.rst
+++ b/documentation/ref-manual/devtool-reference.rst
@@ -328,12 +328,19 @@ Checking on the Upgrade Status of a Recipe
 Upstream recipes change over time. Consequently, you might find that you
 need to determine if you can upgrade a recipe to a newer version.

-To check on the upgrade status of a recipe, use the
-``devtool check-upgrade-status`` command. The command displays a table
-of your current recipe versions, the latest upstream versions, the email
-address of the recipe's maintainer, and any additional information such
-as commit hash strings and reasons you might not be able to upgrade a
-particular recipe.
+To check on the upgrade status of a recipe, you can use the
+``devtool latest-version recipe`` command, which quickly shows the current
+version and the latest version available upstream. To get such information
+for all available recipes, use the ``devtool check-upgrade-status`` command.
+The command displays a table of your current recipe versions, the latest
+upstream versions, the email address of the recipe's maintainer, and any
+additional information such as commit hash strings and reasons you might
+not be able to upgrade a particular recipe.
+
+This upgrade checking mechanism relies on the optional :term:`UPSTREAM_CHECK_URI`,
+:term:`UPSTREAM_CHECK_REGEX`, :term:`UPSTREAM_CHECK_GITTAGREGEX`,
+:term:`UPSTREAM_CHECK_COMMITS` and :term:`UPSTREAM_VERSION_UNKNOWN`
+variables which are defined in package recipes.

 .. note::

@@ -342,9 +349,10 @@ particular recipe.
       file.

    -  If the recipe is using the :ref:`bitbake:bitbake-user-manual/bitbake-user-manual-fetching:git fetcher (\`\`git://\`\`)`
-      rather than a
-      tarball, the commit hash points to the commit that matches the
-      recipe's latest version tag.
+      rather than a tarball, the commit hash points to the commit that matches
+      the recipe's latest version tag, or in the absence of suitable tags,
+      to the latest commit (when :term:`UPSTREAM_CHECK_COMMITS` set to ``1``
+      in the recipe).

 As with all ``devtool`` commands, you can get help on the individual
 command::
@@ -393,6 +401,9 @@ satisfied.
    NOTE: busybox 1.29.2 1.30.0 Andrej Valek <andrej.valek@siemens.com>
    NOTE: dbus-test 1.12.10 1.12.12 Chen Qi <Qi.Chen@windriver.com>

+Last but not least, you may set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1``
+in a recipe when no way is found to determine its latest upstream version.
+
 .. _devtool-upgrading-a-recipe:

 Upgrading a Recipe
diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 2342846dc7..7545e708c6 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -8534,9 +8534,9 @@ system and gives an overview of their function and contents.
       You can perform a per-recipe check for what the latest upstream
       source code version is by calling ``devtool latest-version recipe``.
       If no combination of the :term:`UPSTREAM_CHECK_URI`, :term:`UPSTREAM_CHECK_REGEX`,
-      `UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
+      :term:`UPSTREAM_CHECK_GITTAGREGEX` and :term:`UPSTREAM_CHECK_COMMITS` variables in
       the recipe allows to determine such an latest upstream version,
-      you can set :term:`UPSTREAM_VERSION_UNKNOWN`` to ``1`` in the recipe
+      you can set :term:`UPSTREAM_VERSION_UNKNOWN` to ``1`` in the recipe
       to acknowledge that the check cannot be performed.
       ::

--
2.25.1