From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Wed, 06 Sep 2006 14:59:42 +0200
From: Wolfgang Grandegger <wg@domain.hid>
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Subject: Re: AW: [Xenomai-help] resubmission : memset of heap
	crashes	Xenomai-Task
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: Roderik_Wildenburg@domain.hid, xenomai@xenomai.org

Hi Gilles,

Gilles Chanteperdrix wrote:
> Roderik_Wildenburg@domain.hid wrote:
>  > Dear Gilles,
>  > 
>  > I admit, the mechanism for allocating all memory of the target is not very sophisticated. The idea was, that MAXHEAPBLOCKS*MEMORYCHUNKSIZE is much much more, than memory available (at least with my target (128MB) this is true). I should have mentioned this in the source code, sorry. If your target has more then (MAXHEAPBLOCKS*MEMORYCHUNKSIZE=320MB(approcimate)) memory, you should increase MAXHEAPBLOCKS.
>  > 
>  > If this condition is fulfiled, I think, there should be no illegal memory access. Do you agree ?
>  > 
> 
> A better patch.
> 
> 
> 
> ------------------------------------------------------------------------
> 
> --- heap.c~	2006-09-06 14:27:31.000000000 +0200
> +++ heap.c	2006-09-06 14:37:07.000000000 +0200
> @@ -101,7 +101,15 @@ void display(void *cookie)
>     {
>        memsize+=addsize;
>        if(!(ret=rt_heap_create(&bigheap[i],nbuf,memsize,H_PRIO|H_MAPPABLE)))
> +      {
> +	 if (i > MAXHEAPBLOCKS - 1)
> +	 {
> +	    printf("i= %d is out of bounds, stopping here, avoid later SEGV.\n",
> +		   i);
> +	    exit(EXIT_FAILURE);
> +	 }
>           rt_heap_delete(&bigheap[i]);
> +      }
>     }while(ret==0);
>  
>     memsize>>=1;
> 
> 
> ------------------------------------------------------------------------

I was able to reproduce the problem on my MPC5200 system some time ago
and I have checked the index "i" as well. "i" was not out-of-range, 
IIRC. The problem only shows up on PowerPC., at least Jan was unable
to reproduce it on a x86 system. How could we debug the seg fault. Do
you have a good idea? Would the IPIPE tracer help?

Wolfgang.