diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 8ae5e9e..172e793 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -534,6 +534,12 @@
    optional. It is only needed if the platform makefile specifies that it
    is required in order to build the ``fwu_fip`` target.
 
+-  ``SDEI_SUPPORT``: Setting this to ``1`` enables support for Software
+   Delegated Exception Interface to BL31 image. This defaults to ``0``.
+
+   When set to ``1``, the build option ``EL3_EXCEPTION_HANDLING`` must also be
+   set to ``1``.
+
 -  ``SEPARATE_CODE_AND_RODATA``: Whether code and read-only data should be
    isolated on separate memory pages. This is a trade-off between security and
    memory usage. See "Isolating code and read-only data on separate memory