Generalize Thread Local Storage (TLS) support (#540)

* Generalize Thread Local Storage (TLS) support

FreeRTOS's Thread Local Storage (TLS) support used variables and
functions from newlib, thereby making the TLS support specific to
newlib. This commit generalizes the TLS support so that it can be used
with other c-runtime libraries also. The default behavior for newlib
support is still kept same for backward compatibility.

The application writer would need to set configUSE_C_RUNTIME_TLS_SUPPORT
to 1 in their FreeRTOSConfig.h and define the following macros to
support TLS for a c-runtime library:

1. configTLS_BLOCK_TYPE - Type used to define the TLS block in TCB.
2. configINIT_TLS_BLOCK( xTLSBlock ) - Allocate and initialize memory
   block for the task's TLS Block.
3. configSET_TLS_BLOCK( xTLSBlock ) - Switch C-Runtime's TLS Block to
   point to xTLSBlock.
4. configDEINIT_TLS_BLOCK( xTLSBlock ) - Free up the memory allocated
   for the task's TLS Block.

The following is an example to support TLS for picolibc:

 #define configUSE_C_RUNTIME_TLS_SUPPORT        1
 #define configTLS_BLOCK_TYPE                   void*
 #define configINIT_TLS_BLOCK( xTLSBlock )      _init_tls( xTLSBlock )
 #define configSET_TLS_BLOCK( xTLSBlock )       _set_tls( xTLSBlock )
 #define configDEINIT_TLS_BLOCK( xTLSBlock )

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
3 files changed
tree: 315bbae869aa9d5ec38a8840681ab70e8f3bcc4d
  1. .github/
  2. include/
  3. portable/
  4. .gitmodules
  5. CMakeLists.txt
  6. croutine.c
  7. event_groups.c
  8. GitHub-FreeRTOS-Kernel-Home.url
  9. History.txt
  10. LICENSE.md
  11. list.c
  12. manifest.yml
  13. queue.c
  14. Quick_Start_Guide.url
  15. README.md
  16. stream_buffer.c
  17. tasks.c
  18. timers.c
README.md

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 https://github.com/FreeRTOS/FreeRTOS-Kernel.git

Using SSH:

git clone git@github.com:FreeRTOS/FreeRTOS-Kernel.git

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.

Spelling

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.