diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 15535d4..a856dbb 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -786,6 +786,10 @@
   but unused). This feature is available if trace unit such as ETMv4.x, and
   ETE(extending ETM feature) is implemented. This flag is disabled by default.
 
+- ``ENABLE_TRF_FOR_NS``: Boolean option to enable trace filter control registers
+  access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented but unused),
+  if FEAT_TRF is implemented. This flag is disabled by default.
+
 GICv3 driver options
 --------------------