Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem


ARM execution from System or Supervisor mode

Posted by William Deninger on September 2, 2009
I've recently completed an ARM9 build (LH7A404) and have a question regarding the processor modes using FreeRTOS. The RTOS is configured in a FIQ preemptive mode.

Because the User and System mode share a cpsr, I find it necessary when executing FreeRTOS in the System mode to add enable_fiq's at the end of the FIQ ISR, but find it not necessary if FreeROTS is executed in the supervisor mode.

Does FreeRTOS expect (among other places within it's code) that one execute the kernel in System or Supervisor mode?

And does FreeRTOS expect all the tasks to run in System mode as opposed to User mode?


RE: ARM execution from System or Supervisor mode

Posted by William Deninger on September 2, 2009
I guess to answer my own question, it appears that for the uIP Embedded WEB Server Demo, the vTaskStartScheduler is required to be run from Supervisor mode (http://www.freertos.org/portsam7xiar.html/) Lucky me. That is how I had chosen.


[ Back to the top ]    [ About FreeRTOS ]    [ Privacy ]    [ Sitemap ]    [ ]

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

NXP tweet showing LPC5500 (ARMv8-M Cortex-M33) running FreeRTOS.

Version 10.1.1 of the FreeRTOS kernel is available for immediate download. MIT licensed.

View a recording of the "OTA Update Security and Reliability" webinar, presented by TI and AWS.


FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Espressif ESP32

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers


STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS

Xilinx Microblaze and Zynq partner