static void MPU_Config( void );

int main(void)
{
int32_t timeout = 0xFFFF;
    
    while( ( __HAL_RCC_GET_FLAG( RCC_FLAG_D2CKRDY ) != RESET ) && ( timeout > 0 ) )
    {
        timeout--;
    }
    if ( timeout < 0 )
    {
        Error_Handler();
    }

    /* Enable I-Cache */
    SCB_EnableICache();

    /* Make the AXI memory non-cacheable */
    MPU_Config();
    /* Enable D-Cache */
    SCB_EnableDCache();

    /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
    HAL_Init();
    ...
}

static void MPU_Config( void )
{
    MPU_Region_InitTypeDef MPU_InitStruct;

    /*  Prohibit MPU */
    HAL_MPU_Disable();

    /*  Configure the MPU attributes of AXI SRAM as Write back, Read allocate, Write allocate */
    MPU_InitStruct.Enable           = MPU_REGION_ENABLE;
    MPU_InitStruct.BaseAddress      = 0x24000000;               // AXI memory where ETH descriptors and buffers are stored
    MPU_InitStruct.Size             = MPU_REGION_SIZE_512KB;
    MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
    MPU_InitStruct.IsBufferable     = MPU_ACCESS_NOT_BUFFERABLE;
    MPU_InitStruct.IsCacheable      = MPU_ACCESS_NOT_CACHEABLE;
    MPU_InitStruct.IsShareable      = MPU_ACCESS_SHAREABLE;
    MPU_InitStruct.Number           = MPU_REGION_NUMBER0;
    MPU_InitStruct.TypeExtField     = MPU_TEX_LEVEL1;
    MPU_InitStruct.SubRegionDisable = 0x00;
    MPU_InitStruct.DisableExec      = MPU_INSTRUCTION_ACCESS_ENABLE;

    HAL_MPU_ConfigRegion(&MPU_InitStruct);

    /*Enable MPU */
    HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
}