<p dir="ltr">According to the ARM docs, the instruction in question decodes to "coprocessor data transfer (LDC, STC)". The way that instruction is encoded (with the first four bits == xE), the instruction will be executed every time it's encountered (i.e., not conditionally).</p>
<p dir="ltr">Stanislav, you said you thought the trap was related to HD math and not alignment. Based on what that instruction apparently is, it looks to me like you were on the right track.</p>
<p dir="ltr">Do all ARM variants have an FPU, and if not, could this problem stem from configure et al. determining there's an FPU on a platform where there isn't one?<br>
<br>
Hope this helps someone find and eradicate this bug.</p>
<p dir="ltr">- Larry</p>
<div class="gmail_quote">On Dec 12, 2015 7:04 PM, "Stanislav Sinyagin" <<a href="mailto:ssinyagin@gmail.com">ssinyagin@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><a href="https://freeswitch.org/jira/browse/FS-8651" rel="noreferrer" target="_blank">https://freeswitch.org/jira/browse/FS-8651</a><br>
the source of the problem is quite deep in the sources of spandsp, so<br>
I can't offer a fix.<br>
<br>
<br>
On Thu, Dec 10, 2015 at 10:49 PM, Komar, Jason <<a href="mailto:jkomar@jbox.ca">jkomar@jbox.ca</a>> wrote:<br>
> I get nothing in debug or sip trace. It always dies at mod_spandsp_fax so I<br>
> figured it was in that module. At that point freeswitch just restarts<br>
> without throwing any errors.<br>
><br>
> Kernel log shows:<br>
><br>
> Dec 10 14:16:17 antman kernel: [ 5949.832802] Alignment trap: not handling<br>
> instruction ecb17a01 at [<b44fe32c>]<br>
> Dec 10 14:16:17 antman kernel: [ 5949.834290] Unhandled fault: alignment<br>
> exception (0x001) at 0xb4546e4a<br>
><br>
> The only part of the exception that is the same every time it happens is<br>
> "instruction ecb17a01."<br>
><br>
> I would have just opened a JIRA, but I didn't think this was enough<br>
> information. I have been Googling trying to figure out how to get more info.<br>
><br>
> Jason<br>
><br>
><br>
> On Thu, Dec 10, 2015 at 2:37 PM, Stanislav Sinyagin <<a href="mailto:ssinyagin@gmail.com">ssinyagin@gmail.com</a>><br>
> wrote:<br>
>><br>
>> Hi, I didn't see any errors, but I'm not using fax, and mostly it's<br>
>> bridging the calls and connecting users to a conference. Do you have more<br>
>> debugging information?<br>
>><br>
>> Most probably the source of the problem is that x86 allows unaligned<br>
>> memory access: a word pointer can have any value. And other architectures<br>
>> don't allow this, and require the pointers to be aligned to word boundaries.<br>
>> Mongodb, for example, is known to fail on any non-x86 CPU because of that.<br>
>><br>
>> So, probably mod_spandsp needs an audit.<br>
>><br>
>> On 10 Dec 2015 21:11, "Komar, Jason" <<a href="mailto:jkomar@jbox.ca">jkomar@jbox.ca</a>> wrote:<br>
>>><br>
>>> Your instructions worked great for me building on/for my Odroid-U3 (arm)<br>
>>> running Debian Jessie.<br>
>>><br>
>>> I know you are running on arm at scaleway. Do you ever run into any<br>
>>> alignment issues? I'm getting alignment exception faults receiving faxes and<br>
>>> I'm having trouble pulling any useful debug messages.<br>
>>><br>
>>> Thanks,<br>
>>> Jason<br>
>>><br>
>>> On Mon, Nov 30, 2015 at 9:27 AM, Stanislav Sinyagin <<a href="mailto:ssinyagin@gmail.com">ssinyagin@gmail.com</a>><br>
>>> wrote:<br>
>>>><br>
>>>> hi,<br>
>>>><br>
>>>> I put together the build scenario that I tested for ARM (armhf at<br>
>>>> <a href="http://scaleway.com" rel="noreferrer" target="_blank">scaleway.com</a>), and it should also work for other architectures:<br>
>>>><br>
>>>><br>
>>>> <a href="https://freeswitch.org/confluence/display/FREESWITCH/Building+debs+for+other+architectures" rel="noreferrer" target="_blank">https://freeswitch.org/confluence/display/FREESWITCH/Building+debs+for+other+architectures</a><br>
>>>><br>
>>>> It will be great if someone tests them on other architectures too.<br>
>>>><br>
>>>><br>
>>>> cheers,<br>
>>>> stanislav<br>
>>>><br>
>>>><br>
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><br>
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><br>
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</blockquote></div>