AM3358: RTOS UART_printf issue

The RTOS team have been notified. They will respond here.

Lali,
yes, it is still open.

Tony,

Could you please share a CCS project that would allow me to reproduce this issue on my side, and I can look into it.

Lali

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/791/PRO_5F00_TEST.7z

If you comment these two lines of code from "task1" the program runs ok, or it crashes
        gateKey = GateSwi_enter(gateHead);
        GateSwi_leave(gateHead, gateKey);

-----------------------main code-----------------------

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/* ========================================================================== */
/*                             Include Files                                  */
/* ========================================================================== */

#ifdef __cplusplus
extern "C" {
#endif
#include <xdc/std.h>

#include <xdc/cfg/global.h>
#include <xdc/runtime/System.h>
#include <xdc/runtime/Types.h>

#include <stdio.h>
#include <ti/sysbios/knl/Task.h>
#include <ti/sysbios/knl/Swi.h>
#include <ti/sysbios/gates/GateSwi.h>

#include <ti/sysbios/BIOS.h>
#include <xdc/runtime/Error.h>

#include <ti/board/board.h>
#include <ti/sysbios/hal/Timer.h>
#include <ti/sysbios/knl/Clock.h>
#include <ti/drv/uart/UART_stdio.h>

#include "app_timer.h"

Void myTimerFunc(UArg a0,UArg a1);
Void swi0DataProcess(UArg arg0,UArg arg1);

#ifdef __cplusplus
}
#endif

GateSwi_Handle gateHead;
UInt gateKey;
/* ========================================================================== */
/*                             Func Declare                                   */
/* ========================================================================== */

Void myTimerFunc(UArg a0,UArg a1)
{
    Clock_tick();
}

void task1(UArg arg0, UArg arg1)
{

    char message[32]={0};
    int m_u32FreqFilter=100;
    sprintf(message,"[%s]:%d\n",__FUNCTION__,m_u32FreqFilter);
    while(1)
    {
        gateKey = GateSwi_enter(gateHead);
        UART_printf("task1\n");
        GateSwi_leave(gateHead, gateKey);
    }
}

void swi0DataProcess(UArg arg0,UArg arg1)
{
    int  i=0;;
    gateKey = GateSwi_enter(gateHead);
     i =(++i)%100;
    GateSwi_leave(gateHead, gateKey);
}
/* ========================================================================== */
/*                               Main                                   */
/* ========================================================================== */
int main(void)
{
    /* Call board init functions */
    Board_initCfg boardCfg;

    boardCfg = BOARD_INIT_MODULE_CLOCK |
        BOARD_INIT_PINMUX_CONFIG |
        BOARD_INIT_UART_STDIO;
    //系统模块初始化
    timerClockInit();

    Board_init(boardCfg);

    GateSwi_Params prms;
    Error_Block e;
    Error_init(&e);
    GateSwi_Params_init(&prms);
    gateHead = GateSwi_create(&prms, &e);
    if (gateHead == NULL) {
        printf("error!\n");
    }

    Error_Block eb;
    Error_init(&eb);
    Task_Handle task = NULL;
    Task_Params taskParams;
    Task_Params_init(&taskParams);

    taskParams.priority = 5;
    taskParams.stackSize = 1024;
    task = Task_create(task1, &taskParams, &eb);
    if (task == NULL) {
        System_printf("Task_create() failed!\n");
        BIOS_exit(0);
    }

    BIOS_start();    /* does not return */

    return 0;
}

Hi,

Can you confirm you are not blowing the stack? Do Tools->ROV->BIOS->Scan for Errors after the system crashes.

Also check ROV->Tasks->Detailed and ROV->Hwi->Module to see how close the stack peaks are.

Todd

hi,

Sorry,I don't know what's the means of "blowing the stack".

 Tools->ROV->BIOS->Scan for Errors:

,ti.sysbios.family.arm.exc.Exception,Module,N/A,exception,An exception has occurred!
,ti.sysbios.knl.Semaphore,Basic,(0x80406708),pendElems,Error: Problem scanning pend Queue: JavaException: java.lang.Exception: Target memory read failed at address: 0x413268e4, length: 8This read is at an INVALID address according to the application's section map. The application is likely either uninitialized or corrupt.
,ti.sysbios.knl.Task,Detailed,(0x80406778),blockedOn,Invalid task internal state: pend element address (0x0) is not within the task's stack

ROV->Tasks->Detailed:

,0x804046b4,ti.sysbios.knl.Task.IdleTask,0,Preempted,ti_sysbios_knl_Idle_loop__E,0x0,0x0,780,2048,0x80405580,n/a,n/a,
,0x80406778,,5,Blocked,task1,0x0,0x0,852,1024,0x804067c8,n/a,n/a,Internal Error

ROV->Hwi->Module:

,0x804041c8,...,0,0,1052,16384,0x8055faa8

You can reproduce the problem, which I think is the quickest way to solve the problem.

I'm not familiar with the UART_prinf() code, it's not part of TI-RTOS, but I looked at the disassembly of UART_printf() from your posted project and can see that it's calling Semaphore_pend(). Semaphore_pend() cannot be called when the Swi scheduler is disabled, and GateSwi_enter() disables the Swi scheduler.

So,GateSwi cannot be called when UART_printf was called,

or all Gate cannot be called? What do you mean.

You can use GateMutex, which is based on a Semaphore.

Why do you even want to wrap a Gate around the call to UART_printf()?

I want to print global variables  in the TaskProcess , this variable is calculated in the SwiProcess,  so the global variable should be protected. 

But  GateMutex can't be used in Swi.

user5183560 said:

I want to print global variables  in the TaskProcess , this variable is calculated in the SwiProcess,  so the global variable should be protected.

I guess I don't understand why you need to protect the global variable at all in this case.  If a Swi is calculating a value for the variable, it will complete its calculation before that variable can be used by a Task - there will be no window of inconsistent data.

The UART_printf("...", global_var) will get a snapshot of global_var at the time of the call to UART_printf().  The global_var might get re-calculated by the Swi immediately after the variable is given to UART_printf(), in which case UART_printf() will print the value before this re-calculation, but isn't that the same thing that will happen if you surround UART_printf() with a Gate?  If the Gate is entered and then the Swi immediately *wants* to run but can't because of the Gate, the Swi will run immediately after the Gate is exited and UART_printf() will have printed the pre-re-calculated value (not that you can do this since a Swi can't "wait" or block waiting for a Gate to be released).

What is the point of using the Gate inside the Swi?