_Thread_Dispatch_disable_level gone negative.

Leon Pollak leonp at plris.com
Thu Apr 29 10:23:34 UTC 2010

On Thursday April 29 2010, Nick Thomas wrote:
> Hi,
> I have had problems in the past with _ISR_Nest_Level and
> _Thread_Dispatch_disable_level.
> These sometimes get stuck at 1, so RTEMS thinks it is in a ISR, which
> prevents any tasks from running.
> Still trying to track down the cause of this issue, but it looks like
> something is going wrong in one of the ISR routines, either it's not using
> a conventional return path or something.
> But, some new info now: I have just seen the same problem occur, but
> _Thread_Dispatch_disable_level is 0xffffffff , i.e. -1;
> This is having the same effect, that no tasks get to run.
> But, what could possibly cause this RTEMS variable to go negative.
> I am using RTEMS 4.7.1 on a PowerPC. I know it's an older version of RTEMS,
> but it's too late in the project to change that now.
> Any comments/suggestions are appreciated regarding this issue.
I think I had the similar problem, when 0xffffffff was the value of comtrol 
variable - do not remember exactly its name, but it was something in 
This was the problem in old version of RTEMS which is solved in upper 
Joel pointed me to the corresponding PR number, but I do not remember it 
Anyway, you need to upgrade...:-((
This is what I finally did, although it cost me a lot of efforts...

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