Define default values of macros before first use (#298)

configSTACK_ALLOCATION_FROM_SEPARATE_HEAP was added recently in This macro was
used in portable.h before its default value was defined, resulting in a
warning when built with -Wundef. This changes moves the default value
definition for configSTACK_ALLOCATION_FROM_SEPARATE_HEAP to portable.h
to ensure that it is defined before first use.

portUSING_MPU_WRAPPERS check in mpu_wrappers.h was updated in The new check
results in a warning when built with -Wundef because
portUSING_MPU_WRAPPERS is not defined yet. This changes adds the default
value definition for portUSING_MPU_WRAPPERS to portable.h to ensure that
it is defined before first use.

Signed-off-by: Gaurav Aggarwal <>
3 files changed
tree: 63ace450d974c79ca7777bd929b96d2a526d53a6
  1. .github/
  2. GitHub-FreeRTOS-Kernel-Home.url
  3. History.txt
  5. Quick_Start_Guide.url
  7. croutine.c
  8. event_groups.c
  9. include/
  10. list.c
  11. portable/
  12. queue.c
  13. stream_buffer.c
  14. tasks.c
  15. timers.c

Getting started

This repository contains FreeRTOS kernel source/header files and kernel ports only. This repository is referenced as a submodule in FreeRTOS/FreeRTOS repository, which contains pre-configured demo application projects under FreeRTOS/Demo directory.

The easiest way to use FreeRTOS is to start with one of the pre-configured demo application projects. That way you will have the correct FreeRTOS source files included, and the correct include paths configured. Once a demo application is building and executing you can remove the demo application files, and start to add in your own application source files. See the FreeRTOS Kernel Quick Start Guide for detailed instructions and other useful links.

Additionally, for FreeRTOS kernel feature information refer to the Developer Documentation, and API Reference.

Getting help

If you have any questions or need assistance troubleshooting your FreeRTOS project, we have an active community that can help on the FreeRTOS Community Support Forum.

Cloning this repository

To clone using HTTPS:

git clone

Using SSH:

git clone

Repository structure

  • The root of this repository contains the three files that are common to every port - list.c, queue.c and tasks.c. The kernel is contained within these three files. croutine.c implements the optional co-routine functionality - which is normally only used on very memory limited systems.

  • The ./portable directory contains the files that are specific to a particular microcontroller and/or compiler. See the readme file in the ./portable directory for more information.

  • The ./include directory contains the real time kernel header files.

Code Formatting

FreeRTOS files are formatted using the “uncrustify” tool. The configuration file used by uncrustify can be found in the FreeRTOS/FreeRTOS repository.


lexicon.txt contains words that are not traditionally found in an English dictionary. It is used by the spellchecker to verify the various jargon, variable names, and other odd words used in the FreeRTOS code base. If your pull request fails to pass the spelling and you believe this is a mistake, then add the word to lexicon.txt. Note that only the FreeRTOS Kernel source files are checked for proper spelling, the portable section is ignored.