diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 9415871..94c12de 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -1079,10 +1079,11 @@
   ``FEATURE_DETECTION`` mechanism. The default is 0 and it is automatically
   disabled when the target architecture is AArch32.
 
-- ``ENABLE_SYS_REG_TRACE_FOR_NS``: Boolean option to enable trace system
+- ``ENABLE_SYS_REG_TRACE_FOR_NS``: Numeric value to enable trace system
   registers access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented
   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.
+  ETE(extending ETM feature) is implemented. This flag can take the values
+  0 to 2, to align with the ``FEATURE_DETECTION`` mechanism. The default is 0.
 
 - ``ENABLE_TRF_FOR_NS``: Numeric value to enable trace filter control registers
   access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented but unused),