| Chris Kay | cda8921 | 2021-08-17 16:24:57 +0100 | [diff] [blame] | 1 | Activity Monitors |
| 2 | ================= |
| 3 | |
| 4 | FEAT_AMUv1 of the Armv8-A architecture introduces the Activity Monitors |
| 5 | extension. This extension describes the architecture for the Activity Monitor |
| 6 | Unit (|AMU|), an optional non-invasive component for monitoring core events |
| 7 | through a set of 64-bit counters. |
| 8 | |
| 9 | When the ``ENABLE_AMU=1`` build option is provided, Trusted Firmware-A sets up |
| 10 | the |AMU| prior to its exit from EL3, and will save and restore architected |
| 11 | |AMU| counters as necessary upon suspend and resume. |
| 12 | |
| Chris Kay | f11909f | 2021-08-19 11:21:52 +0100 | [diff] [blame^] | 13 | Auxiliary counters |
| 14 | ------------------ |
| 15 | |
| 16 | FEAT_AMUv1 describes a set of implementation-defined auxiliary counters (also |
| 17 | known as group 1 counters), controlled by the ``ENABLE_AMU_AUXILIARY_COUNTERS`` |
| 18 | build option. |
| 19 | |
| 20 | As a security precaution, Trusted Firmware-A does not enable these by default. |
| 21 | Instead, platforms may configure their auxiliary counters through one of two |
| 22 | possible mechanisms: |
| 23 | |
| 24 | - |FCONF|, controlled by the ``ENABLE_AMU_FCONF`` build option. |
| 25 | - A platform implementation of the ``plat_amu_topology`` function (the default). |
| 26 | |
| 27 | See :ref:`Activity Monitor Unit (AMU) Bindings` for documentation on the |FCONF| |
| 28 | device tree bindings. |
| 29 | |
| Chris Kay | cda8921 | 2021-08-17 16:24:57 +0100 | [diff] [blame] | 30 | -------------- |
| 31 | |
| 32 | *Copyright (c) 2021, Arm Limited. All rights reserved.* |