Re: [ECOS] using threads causes exceptions

[Gary Thomas <gary at mlbassoc dot com>]

On Wed, 2005-08-03 at 18:07 +0200, Stefan Sommerfeld wrote:
> Hi,
> >> >>
> >> >> I'm using eCos on an XScale PXA270 and i have a problem using 
> >> >> threads.
> >> >> My
> >> >> program does only start a thread from main() and after this function
> >> >> calls
> >> >> from thread causes ABORT DATA exceptions (MMU info: Imprecise 
> >> >> External
> >> >> Data
> >> >> Abort). Even a printf causes this exception. The strange thing is, 
> >> >> the
> >> >> eCos
> >> >> thread tests are working, even the stress test. Do i have to do some
> >> >> initialisation? Should i better use cyg_start() instead of main()?
> >> >
> >> > Using main() is just fine.  Most likely, you've not created the
> >> > stack for the thread correctly.  Or perhaps it's something within
> >> > your thread itself.
> >> >
> >> > Have you tried running the program using GDB?  Then you can catch
> >> > the culprit and know where to start looking.
> >>
> >> So ... made it through gdb which gave me:
> >> [New Thread 2]
> >>
> >> Program received signal SIGTRAP, Trace/breakpoint trap.
> >> [Switching to Thread 2]
> >> 0xa008c72c in main_stack ()
> >>
> >> This version is a bit smaller and does give me no exceptions like ABORT
> >> DMA, but only the gdb output. Any suggestions?
> >
> > It's pretty obvious that you've not set your thread up properly
> > since it's trying to execute from the stack!  Look carefully at
> > how you created the thread - compare it against the examples and
> > tests.
> 
> >From gdb it looks like a corrupt stack, but i don't why.
> 
> > If you still can't figure out what's wrong, you could send a
> > *fragment* of your code, showing how you are creating the thread,
> > etc.  Note: we don't want/need to see your whole program, just
> > this portion.
> 
> #define STACK_SIZE (CYGNUM_HAL_STACK_SIZE_TYPICAL*2)
> 
> static cyg_thread thread_data;
> static cyg_handle_t thread_handle;
> 
> static void decoder_audio(cyg_addrword_t data)
> {
>  diag_printf("i'm here\n");
>  // more complex C++ stuff here
>  // and a endless loop calling some methods
> }
> 
> 
> int main(void)
> {
>  void *stack = malloc(STACK_SIZE);
> 
>  cyg_thread_create(0,                // Priority - just a number
>   test_thread,          // entry
    ^^^^^^^^^^^

What is this?  It should be the entry point to your thread - maybe
'decoder_audio'?

>   0,                 // entry parameter
>   0,    // Name
>   stack,         // Stack
>   STACK_SIZE,        // Size
>   &thread_handle,    // Handle
>   &thread_data       // Thread data structure
>   );
>  cyg_thread_resume(thread_handle);  // Start it
>  cyg_scheduler_start();
> 
>  printf("main end\n");
> }
> 
> I even tried 1MB stack size with no change.
> 
> Bye... 
> 
> 
-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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