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Making FreeRTOS "static"?

Posted by freddie-chopin on October 14, 2013

Recently I had this idea, that it would be great to make it possible to use only static (pre-allocated) data blocks in FreeRTOS, as opposed to using data coming from malloc(). The change would be 100% backward compatible.

Now we have xTaskCreate() which takes stack size as parameter. I propose to add xTaskCreateStatic() which would take stack size AND pointer to data block of this size. "Old" xTaskCreate() would just do sth like that:

xTaskCreate(...) { uint8t *stack = malloc(stacksize); return xTaskCreateStatic(..., stack, stack_size); }

And xTaskCreateStatic() would do everything xTaskCreate() was doing, but not the allocation. This way all old code would work without changes, and one could completely remove dependancy on malloc() from FreeRTOS.

The same goes for other functions that use malloc() - creating of semaphores, mutexes, queues, ...

I understand that the xTaskCreate() function also allocates data block for TCB, but I guess this could be done some way too, for example the static version would just need a pointer to preallocated tskTCB object. This object would need to be made public, probably the same would be true for other handles to objects (xSemaphoreHandle etc.).

What do you think?

Regards, FCh


Making FreeRTOS "static"?

Posted by richardbarry on October 14, 2013

Look at the function xTaskCreateRestricted(): http://www.freertos.org/xTaskCreateRestricted.html

It calls xTaskGenericCreate(). Although it is not documented, you can call xTaskGenericCreate() directly to pass in a pre-allocated stack and TCB.

Regards.


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