1.2 KiB
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.
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.
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Docutils System Messages
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