Issue with VSI interface and RTOS

[christophe0606]

I have used vsi interface in the past but recently when trying to use it again I have had a weird problem.
It works when called from main but does not work when called from a thread.

I am using FVP_Corstone_SSE-300_Ethos-U55 from avh-fvp 11.31.28

I am using vsi audio.
I have removed any audio server from the Python to have the simplest possible thing.

I have enabled DEBUG log in the python.

When I initialize the vStream interface from main, I can see DEBUG messages from Python.
When I initialize from a thread : nothing.

I have attempted a simpler thing : just writing to a register with AudioIn->CONTROL = 0U;

When I do it from main I see the debug messages from Python.
When I do it from a thread : nothing.

My thread is created using CMSIS RTOS API using following attributes:

const osThreadAttr_t app_main_attr = {
  .name = "app_main",
  .stack_size = 4096,
  .priority = osPriorityNormal
};

The thread is:

void app_main (void *argument)
 {
    printf("Started\n");
    AudioIn->CONTROL = 0U; // To debug
   
   stream_configure_and_start();
}

The print is here to confirm the thread is started and running. I see the print in the console.

The OS is started with:

printf("Hello, World!\n");

osStatus_t err = osKernelInitialize();
if (err != osOK) {
        CMSISSTREAM_LOG_ERR("Kernel initialization failed\n");
        goto error;
    }

osThreadNew(app_main, NULL, &app_main_attr);    // Create application main thread

printf("Start kernel\n");

// Hand control to the RTOS scheduler.
osKernelStart();

When I do AudioIn->CONTROL = 0U; in main before starting the RTOS, I can see the debug message in Python. The wrRegs python function is called.

In summary, I can't make vsi/vstream work when started from a thread.