From 755aee4178d4dc7a3fac555b963359235285063f Mon Sep 17 00:00:00 2001
From: Yi Ying <yiying@espressif.com>
Date: Mon, 27 Jul 2020 14:40:47 +0800
Subject: [PATCH] add a note about ESP-IDF FreeRTOS version

---
 docs/en/api-reference/system/freertos.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docs/en/api-reference/system/freertos.rst b/docs/en/api-reference/system/freertos.rst
index 47dc80eba2..b18e9eab9c 100644
--- a/docs/en/api-reference/system/freertos.rst
+++ b/docs/en/api-reference/system/freertos.rst
@@ -6,6 +6,9 @@ Overview
 
 This section contains documentation of FreeRTOS types, functions, and macros. It is automatically generated from FreeRTOS header files.
 
+.. note::
+    ESP-IDF FreeRTOS is based on the Xtensa port of FreeRTOS v8.2.0, however some functions of FreeRTOS v9.0.0 have been backported. See the :ref:`backported-features` for more information.
+
 For more information about FreeRTOS features specific to ESP-IDF, see :doc:`ESP-IDF FreeRTOS SMP Changes<../../api-guides/freertos-smp>`
 and :doc:`ESP-IDF FreeRTOS Additions<freertos_additions>`.