diff --git a/docs/getting_started/build-internals.rst b/docs/getting_started/build-internals.rst
index 390c367..c43f4e9 100644
--- a/docs/getting_started/build-internals.rst
+++ b/docs/getting_started/build-internals.rst
@@ -19,3 +19,11 @@
   ``HANDLE_EA_EL3_FIRST_NS`` is set. Currently only NS world routes EA to EL3 but
   in future when Secure/Realm wants to use FFH then they can introduce new macros
   which will enable this option implicitly.
+
+-  ``OPTEE_SP_FW_CONFIG``: DTC build flag to include OP-TEE as SP in
+   tb_fw_config device tree. This flag is defined only when
+   ``ARM_SPMC_MANIFEST_DTS`` manifest file name contains pattern optee_sp.
+
+-  ``TRUSTY_SP_FW_CONFIG``: DTC build flag to include Trusty as SP in
+   tb_fw_config device tree. This flag is defined only when
+   ``ARM_SPMC_MANIFEST_DTS`` manifest file name contains pattern trusty_sp.