diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 36b167940a..2e59e49f82 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -6688,6 +6688,18 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
                     internal toolchain.
                     The variable's default value is "default", which uses
                     that internal toolchain.
+                    <note>
+                        If <filename>TCMODE</filename> is set to a value
+                        other than "default", then it is your responsibility
+                        to ensure that the toolchain is compatible with the
+                        default toolchain.
+                        Using older or newer versions of these components
+                        might cause build problems.
+                        See the
+                        <ulink url='&YOCTO_RELEASE_NOTES;'>Release Notes</ulink>
+                        for the specific components with which the toolchain
+                        must be compatible.
+                    </note>
                 </para>
 
                 <para>