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FreeRtos, native Floats and Task switching

Posted by cdebrebisson on April 24, 2017

Hello,

I am working with an ARM Cortex A7 running FreeRTOS and I am having a problem. I have 2 tasks, running in parallel, computing different parts of mandelbrot set. It does not work -:( Note that running only one of the 2 tasks works perfectly!

However, if I change the code for my task so that it uses ints (with 12 bit fixed point arithmetics), then there is no issues and I can do both calculations in parallel...

It feels that FreeRTOS does not task switch the FPU registers. Is this assumption correct? If yes, what other registers are not switched (NEON, ...)

Regards, Cyrille


FreeRtos, native Floats and Task switching

Posted by rtel on April 24, 2017

See the section "using the floating point unit" on the following page: http://www.freertos.org/Using-FreeRTOS-on-Cortex-A-Embedded-Processors.html

Exactly what you need to do depends on the compiler you are using and the version of FreeRTOS you are using.


FreeRtos, native Floats and Task switching

Posted by glenenglish on April 24, 2017

I can't find configUSETASKFPU_SUPPORT anywhere in any source files.... using 9.0..... ?


FreeRtos, native Floats and Task switching

Posted by rtel on April 24, 2017

There are a few different Cortex-A ports, some with GIC support some with proprietary interrupt controller support, and for different compilers. configUSETASKFPUSUPPORT is in this version: FreeRTOSSourceportableGCCARMCA9


FreeRtos, native Floats and Task switching

Posted by glenenglish on April 25, 2017

ta. that's why I am not seeing it, it's in one of the ports. very good. thanks.


FreeRtos, native Floats and Task switching

Posted by cdebrebisson on April 25, 2017

Hello,

Thanks for your help, I did discover the configUSETASKFPU_SUPPORT define and the vPortTaskUsesFPU(); function call.

It does work now!

Thanks!

Cyrille


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