From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 13 Nov 2008 19:27:57 +0100
From: Wolfgang Grandegger <wg@domain.hid>
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Subject: Re: [Xenomai-help] Mode switch when using RT heap on ARM
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: xenomai-help <xenomai@xenomai.org>

Gilles Chanteperdrix wrote:
> Wolfgang Grandegger wrote:
>> Hello,
>>
>> I realized that accessing memory allocated with rt_heap_alloc() causes
>> mode switches on ARM i.mx31. The attached patch provides a demo program
>> to demonstrate the problem, which actually does *not* show up on my
>> PowerPC TQM5200 board.
> 
> Ok. I ran your test on an ARMv5 using an old version of Xenomai, and I
> only get a fault on first write to the heap, being either cached or non
> cached.
> 
> I will now run the tests on AT91RM9200 with a more recent version of
> xenomai to confirm that we get the same effect, but if we do, this means
> that we are facing an armv6 specific issue and that for a workaround, we
> need to understand armv6 memory management.

The problem seems to be more general. I have now use the TLSF allocator
from Xenomai-solo for dynamic memory allocation and I still see the mode
switch counter increasing. Again, no problems on my TQM5200 PowerPC
board. I have the impression that the problems are related to armv6.

Wolfgang.