Interrupt Problems (again).

[Joel Sherrill]

On 02/12/2010 11:55 AM, Gedare Bloom wrote:
> I haven't been using RTEMS that long, so I don't have much advice for
> you, but I did have one thought to share.
>
> Perhaps something strange is going on with a CPU dependent
> implementation of _ISR_Is_in_progress. Try this:
>   >  cd ${RTEMS}/cpukit/score/cpu/powerpc/rtems
>   >  grep -r CPU_PROVIDES_ISR_IS_IN_PROGRESS *
>
> If you get back something that says TRUE, that gives you something
> else to look for. score relies on _ISR_Nest_level to determine whether
> or not an interrupt is happening, but I suppose a mismatch between
> _ISR_Nest_level and the result of rtems_interrupt_is_in_progress()
> could be caused by a port that provides an alternate implementation of
> _ISR_Is_in_progress.
>
> AFAIK there aren't any ports that actually use this option in the
> current release...
>    
The PowerPC has kept the level in a register and since old
RTEMS PowerPC had BSP specific interrupt entry
and exit code, it could be incorrect in a BSP specific way.

2003-07-18      Till Straumann <strauman at slac.stanford.edu>

         PR 288/rtems
         * rtems/new-exceptions/cpu.h: _ISR_Nest_level is now properly
         maintained and does not reside in SPRG0.

I would be suspicious of your .S code that is CPU model or
BSP specific.

--joel
> -Gedare
>
> On Fri, Feb 12, 2010 at 11:47 AM, Nick Thomas<nick.thomas at pixsan.com>  wrote:
>    
>> Hi,
>>
>> I am still having problems with interrupts.
>>
>> I reported a while ago that rtems_interrupt_is_in_progress() was returning
>> the wrong value occasionally.
>> Now, I see that I am getting an error 18 (RTEMS_CALLED_FROM_ISR) at a place
>> in the code that definitely back-traces to a task!
>>
>> At the point of the crash I see that _ISR_Nest_level is zero, and
>> _Thread_Dispatch_disable_level is 1 .
>>
>> I am using RTEMS 4.7.1 on a PowerPC 405, if that helps.
>>
>> I know that RTEMS 4.7.1 is quite old now, but I don't realistically have the
>> ability to upgrade at this point in the project.
>>
>>
>> Any help/comments/suggestions welcomed.
>>
>>
>> Regards
>>
>> Nick
>>
>> -----------------------------
>> Nick Thomas
>> Email: nick.thomas at pixsan.com
>>
>>
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>>
>>      
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>    


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