From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <491C7089.4020206@domain.hid> Date: Thu, 13 Nov 2008 19:23:05 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <491805AE.1060809@domain.hid> <491C6A95.9000802@domain.hid> <491C71AD.5010103@domain.hid> In-Reply-To: <491C71AD.5010103@domain.hid> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Mode switch when using RT heap on ARM List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wolfgang Grandegger Cc: xenomai-help Wolfgang Grandegger wrote: > 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. That is because you do unaligned accesses, on ARM they generate faults. -- Gilles.