diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 07ed143ac5606617c720301ac6621355a341f90a..8cfb978e795e43e3ef25f3e18e11baf7c2a28d54 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -7880,6 +7880,39 @@ system and gives an overview of their function and contents.
          might break at runtime if the interface of the recipe was changed
          after the other had been built.
 
+   :term:`SIGGEN_LOCKEDSIGS`
+     The list of locked taks, with the form::
+
+       SIGGEN_LOCKEDSIGS += "<package>:<task>:<signature>"
+
+     If ``<signature>`` exists for the specified ``<task>`` and ``<package>``
+     in sstate, BitBake will use the cached output instead of rebuilding the
+     ``<task>``. If it does not exist, BitBake will build the ``<task>`` and
+     the sstate will be used next time.
+
+   :term:`SIGGEN_LOCKEDSIGS_TASKSIG_CHECK`
+     Specifies the debug level of task signature check. 3 levels are supported:
+
+     * info: displays a "Note" message to remind user that a task is locked
+       and current signature matches the locked one.
+     * warn: displays a "Warning" message if a task is locked and current
+       signature does not match the locked one.
+     * error: same as warn but displays an “Error” message and abort.
+
+   :term:`SIGGEN_LOCKEDSIGS_TYPES`
+     Allowed overrides for :term:`SIGGEN_LOCKEDSIGS`. This is mainly used
+     for achitecture specific lock. A common value for :term:`SIGGEN_LOCKEDSIGS_TYPES`
+     is ``${PACKAGE_ARCHS}``::
+
+       SIGGEN_LOCKEDSIGS_TYPES += "${PACKAGE_ARCHS}"
+
+       SIGGEN_LOCKEDSIGS_core2-64 += "bc:do_compile:abcd"
+       SIGGEN_LOCKEDSIGS_cortexa57 += "bc:do_compile:efgh"
+
+     Here, the ``do_compile`` task from ``bc`` will be locked only for
+     ``x86-64`` and ``arm64`` but not for other architectures such as
+     ``qemumips``.
+
    :term:`SITEINFO_BITS`
       Specifies the number of bits for the target system CPU. The value
       should be either "32" or "64".