diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 2892dc6..4146e33 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -23,8 +23,9 @@
    is expected to contain a makefile called ``<aarch32_sp-value>.mk``.
 
 -  ``AMU_RESTRICT_COUNTERS``: Register reads to the group 1 counters will return
-   zero at all but the highest implemented exception level.  Reads from the
-   memory mapped view are unaffected by this control.
+   zero at all but the highest implemented exception level. External
+   memory-mapped debug accesses are unaffected by this control.
+   The default value is 1 for all platforms.
 
 -  ``ARCH`` : Choose the target build architecture for TF-A. It can take either
    ``aarch64`` or ``aarch32`` as values. By default, it is defined to