RTOS/AM5728: HWI hangs

Tool/software: TI-RTOS

I am developing mailbox communication between DSP and PRU on AM5728IDK. In theory, PRU program is user1 of mailbox2, configure mailbox2 and send a message to queue0 of mailbox2. And DSP program is user0 of mailbox2, receive a interrupt and read the message from queue0 of mailbox2. But when the DSP program received a interrupt, it hangs in Hwi_unPluggedInterrupt().

There are the DSP program snippet:

Int main()
{
    Task_Handle task;
    Error_Block eb;
    Hwi_Params params;

    IntXbar_connectIRQ(43, 237);


    EventCombiner_dispatchPlug(43, &myEvent43Fxn, 43, TRUE);

    EventCombiner_enableEvent(43);

    Hwi_Params_init(&params);

    params.eventId = 43/32 ;

    params.arg =  params.eventId;

    params.maskSetting = Hwi_MaskingOption_SELF;

    params.enableInt = TRUE;

    Hwi_create(7, mailbox_ISR, &params, &eb);


    System_printf("DSP:enter main()\n");
    System_flush();

    Error_init(&eb);
    task = Task_create(taskFxn, NULL, &eb);
    if (task == NULL) {
        System_printf("Task_create() failed!\n");
        BIOS_exit(0);
    }

    BIOS_start();    /* does not return */
    return(0);
}


void mailbox_ISR(UArg arg)
{

    gMsgStatus = MailboxGetMessage(MAILBOX_BASE_ADDRESS, MAILBOX_QUEUE_0,
                                  (uint32_t *) &gMsg);

    MailboxClrNewMsgStatus(MAILBOX_BASE_ADDRESS, MAILBOX_USER, MAILBOX_QUEUE_0);
}

Void taskFxn(UArg a0, UArg a1)
{
    System_printf("DSP:enter taskFxn()\n");
    System_flush();

    int i = 0;

    Hwi_enableInterrupt(7);

    Hwi_enable();

    Hwi_startup();

    ...
}


environment:
CCS 6.2
TI-RTOS:ti-processor-sdk-rtos-am57xx-evm-04.00.00.04

I don't know how to debug the Hwi and interrupt. Please give me some guides.

Thank you.