RSB and C++ Model

[Joel Sherrill]

On 3/24/2014 11:29 PM, Chris Johns wrote:
> On 25/03/2014 4:41 am, Joel Sherrill wrote:
>> On 3/24/2014 12:36 PM, Sebastian Huber wrote:
>>> On 03/24/2014 06:14 PM, Joel Sherrill wrote:
>>>> Hi
>>>>
>>>> My most recently built toolset seems to be using pthreads instead
>>>> of the RTEMS thread code. Any ideas?
>>>>
>>> Its due to this patch:
>>>
>>> http://git.rtems.org/rtems-tools/tree/tools/4.11/gcc/gcc-rtems-thread-model-posix-1.diff
>>>
>>> We should really avoid using the POSIX GCC thread model.  Its too
>>> dangerous due to the silent errors.
> Yes this is true but it did not fail in the way the RTEMS wrapper did 
> with SMP. I felt it was the lesser of 2 bad situations.
>
> I also suspect the issue with gcc and the POSIX thread support is still 
> open and will need to be addressed. As far as I understand the mingw64 
> tools uses POSIX rather than the win32 thread model with an add on 
> pthread library.
We need to propose a target specific macro to gcc to do something based on
the status code. Something like a G++ run-time specific assert that the
target
can tailor. We really want to know about failures, I am not so sure that
other
targets do.

It will be hard for a user to debug random C++ run-time failures from
resource
allocation problems.

FWIW having run into this problem porting things, there is a debug
printk at the
bottom of _Objects_Allocate() to report just this situation.  Any
allocation of anything
with an ID fails at this single point. It is a handy debug thing but
there may be a way
to generalize this.
>> I knew the patch and the problem. I was surprised it was included and
>> wanted to confirm that we agreed it shouldn't be.
>>
>> Should I put together a patch for the RSB?
>>
> If we keep using the wrapper that is fine and I will review a patch once 
> the gxx wrapper changes to fix it have been completed and merged into 
> master. Sebastian, how is the gxx_wrapper code tested ?
>
> Long term I feel the posix thread model maybe a better path because it 
> means we need just one supported interface with gcc. The c++11 threading 
> support will also require pthreads.
>
> Chris

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at OARcorp.com        On-Line Applications Research
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