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- 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_FEAT_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.*
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