ref-manual/variables.rst: document the REQUIRED_MACHINE_FEATURES variable

Added in OE-Core commit: 5f4875b950ce ("distro_features_check: expand
with MACHINE_FEATURES and COMBINED_FEATURES, rename").

Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
(From yocto-docs rev: c0551456cba6016d5014c2be8d6906e58a324cc4)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 5af64a0181..40232ba0e0 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -7950,6 +7950,15 @@ system and gives an overview of their function and contents.
       the recipe will be skipped, and if the build system attempts to build
       the recipe then an error will be triggered.
 
+   :term:`REQUIRED_MACHINE_FEATURES`
+      When inheriting the :ref:`ref-classes-features_check` class, this variable
+      identifies :term:`MACHINE_FEATURES` that must exist in the current
+      configuration in order for the :term:`OpenEmbedded Build System` to build
+      the recipe. In other words, if the :term:`REQUIRED_MACHINE_FEATURES` variable
+      lists a feature that does not appear in :term:`MACHINE_FEATURES` within the
+      current configuration, then the recipe will be skipped, and if the build
+      system attempts to build the recipe then an error will be triggered.
+
    :term:`REQUIRED_TUNE_FEATURES`
       When inheriting the :ref:`ref-classes-features_check` class, this variable
       identifies tune features that must exist in the current configuration in