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diff --git a/docs/components/activity-monitors.rst b/docs/components/activity-monitors.rst new file mode 100644 index 000000000..dd45c4353 --- /dev/null +++ b/docs/components/activity-monitors.rst @@ -0,0 +1,34 @@ +Activity Monitors +================= + +FEAT_AMUv1 of the Armv8-A architecture introduces the Activity Monitors +extension. This extension describes the architecture for the Activity Monitor +Unit (|AMU|), an optional non-invasive component for monitoring core events +through a set of 64-bit counters. + +When the ``ENABLE_AMU=1`` build option is provided, Trusted Firmware-A sets up +the |AMU| prior to its exit from EL3, and will save and restore architected +|AMU| counters as necessary upon suspend and resume. + +.. _Activity Monitor Auxiliary Counters: + +Auxiliary counters +------------------ + +FEAT_AMUv1 describes a set of implementation-defined auxiliary counters (also +known as group 1 counters), controlled by the ``ENABLE_AMU_AUXILIARY_COUNTERS`` +build option. + +As a security precaution, Trusted Firmware-A does not enable these by default. +Instead, platforms may configure their auxiliary counters through one of two +possible mechanisms: + +- |FCONF|, controlled by the ``ENABLE_AMU_FCONF`` build option. +- A platform implementation of the ``plat_amu_topology`` function (the default). + +See :ref:`Activity Monitor Unit (AMU) Bindings` for documentation on the |FCONF| +device tree bindings. + +-------------- + +*Copyright (c) 2021, Arm Limited. All rights reserved.* |