simple binary semaphore + priority inheritance

Till Straumann strauman at
Sun Oct 18 00:06:25 UTC 2009

Joel Sherrill wrote:
> That combination never really worked.  The create let it slip through 
> and treated it as simple with priority -- no inheritance. Inheritance 
> needs the mutex to be allocated and deallocated by the same thread.  
> That is in conflict with the requirement that a simple binary 
> semaphore can be used for condition synchronization from an interrrupt.
> Hope that is clear.
It is - but IMHO this should be mentioned in the documentation.
I didn't find any hint that priority inheritance for simple binary
semaphores is illegal but maybe I missed somehing.

> --joel
>> On Oct 17, 2009 5:11 PM, "Till Straumann" <strauman at 
>> <mailto:strauman at>> wrote:
>> I see that on the HEAD simple binary semaphores no
>> longer are allowed to have the RTEMS_INHERIT_PRIORITY
>> (nor the RTEMS_PRIORITY_CEILING) attribute.
>> What is the reason for this change? I suspect this
>> will break quite a few applications.
>> -- Till

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