[Mono-dev] NRE when using pointers on armhf

[Slide]

Thanks for the confirmation. I appreciate the help!

On Thu, Mar 26, 2015 at 3:11 PM Zoltan Varga <vargaz at gmail.com> wrote:

> Hi,
>
>  Mono sets up signal handlers in order to implement throwing null
> reference exceptions. This means that some SIGSEGVs etc. get converted to
> NullReferenceExceptions.
>
>               Zoltan
>
> On Thu, Mar 26, 2015 at 5:37 PM, Slide <slide.o.mix at gmail.com> wrote:
>
>> Yes, I can tell that the pointer is unaligned, I was wondering why I
>> would get a NullReferenceException for an unaligned access. I would assume
>> that mono sets up some handler or something that catches unaligned
>> exceptions? Maybe not?
>>
>> On Thu, Mar 26, 2015 at 2:23 PM Brandon Perry <bperry.volatile at gmail.com>
>> wrote:
>>
>>> Could also cast to an IntPtr and check the Size property, which would
>>> return the number of bytes in the pointer?
>>>
>>>
>>> https://msdn.microsoft.com/en-us/library/system.intptr.size%28v=vs.110%29.aspx
>>>
>>> Might be misunderstanding the issue though.
>>>
>>> On Thu, Mar 26, 2015 at 4:20 PM, Zoltan Varga <vargaz at gmail.com> wrote:
>>>
>>>> Hi,
>>>>
>>>>   You can check whenever the pointer is aligned by converting it into
>>>> an int.
>>>>
>>>>              Zoltan
>>>>
>>>> On Thu, Mar 26, 2015 at 4:53 PM, Slide <slide.o.mix at gmail.com> wrote:
>>>>
>>>>> That's a good point! Can you tell me where in the mono code that the
>>>>> unaligned accesses are handled? I'd just like to confirm.
>>>>>
>>>>> Thanks!
>>>>>
>>>>> slide
>>>>>
>>>>> On Thu, Mar 26, 2015 at 1:13 PM Zoltan Varga <vargaz at gmail.com> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>>  arm might require aligned reads, i.e. 'p' should be 4 byte aligned
>>>>>> in this case.
>>>>>>
>>>>>>           Zoltan
>>>>>>
>>>>>> On Thu, Mar 26, 2015 at 3:28 PM, Slide <slide.o.mix at gmail.com> wrote:
>>>>>>
>>>>>>> I am trying to compile and use the ZeroC Ice remoting library for
>>>>>>> armhf to run on my RaPi 2. The compilation goes fine, but when running the
>>>>>>> test suite I am getting a NullReferenceException on the pointer assignment
>>>>>>> in the following code:
>>>>>>>
>>>>>>> fixed(byte* p = &_bytes[_position])
>>>>>>> {
>>>>>>>     *((float*)p) = _valBytes.floatVal; // exception here
>>>>>>> }
>>>>>>>
>>>>>>> This same code works on x86_64, so I am assuming there is something
>>>>>>> that is missing in the armhf implementation.
>>>>>>>
>>>>>>> Is there something I can do to debug what might be missing and
>>>>>>> provide a patch? I've never done work on the mono runtime itself.
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> slide
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Mono-devel-list mailing list
>>>>>>> Mono-devel-list at lists.ximian.com
>>>>>>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>>>>>>
>>>>>>>
>>>>>>
>>>>
>>>> _______________________________________________
>>>> Mono-devel-list mailing list
>>>> Mono-devel-list at lists.ximian.com
>>>> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>>>
>>>>
>>>
>>>
>>> --
>>> http://volatile-minds.blogspot.com -- blog
>>> http://www.volatileminds.net -- website
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ximian.com/pipermail/mono-devel-list/attachments/20150326/504dec78/attachment-0001.html>