1*9cf75647SChris KayActivity Monitors 2*9cf75647SChris Kay================= 3*9cf75647SChris Kay 4*9cf75647SChris KayFEAT_AMUv1 of the Armv8-A architecture introduces the Activity Monitors 5*9cf75647SChris Kayextension. This extension describes the architecture for the Activity Monitor 6*9cf75647SChris KayUnit (|AMU|), an optional non-invasive component for monitoring core events 7*9cf75647SChris Kaythrough a set of 64-bit counters. 8*9cf75647SChris Kay 9*9cf75647SChris KayWhen the ``ENABLE_AMU=1`` build option is provided, Trusted Firmware-A sets up 10*9cf75647SChris Kaythe |AMU| prior to its exit from EL3, and will save and restore architected 11*9cf75647SChris Kay|AMU| counters as necessary upon suspend and resume. 12*9cf75647SChris Kay 13*9cf75647SChris Kay-------------- 14*9cf75647SChris Kay 15*9cf75647SChris Kay*Copyright (c) 2021, Arm Limited. All rights reserved.* 16