From 0db1989fb747e772fffe781e5c437fb5a86bb8a3 Mon Sep 17 00:00:00 2001
From: stnolting <stnolting@gmail.com>
Date: Sat, 8 Feb 2025 09:51:01 +0100
Subject: [PATCH] [docs] add AMO HPM note

---
 docs/datasheet/cpu_csr.adoc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/docs/datasheet/cpu_csr.adoc b/docs/datasheet/cpu_csr.adoc
index 2fc8f3ff3..28a2e3e74 100644
--- a/docs/datasheet/cpu_csr.adoc
+++ b/docs/datasheet/cpu_csr.adoc
@@ -761,6 +761,11 @@ caused by a fence instruction, a control flow transfer or a instruction fetch bu
 The CPU HPM/counter logic treats all executed instruction as "retired" even if they raise an exception,
 cause an interrupt, trigger a privilege mode change or were not meant to retire (i.e. claimed by the RISC-V spec.).
 
+.Atomic Memory Access
+[NOTE]
+The read-modify-write instructions of the <<_zaamo_isa_extension>> operate as simple load for the CPU hardware.
+Hence, they will only trigger `HPMCNT_EVENT_LOAD` and only once.
+
 
 {empty} +
 [discrete]