rtems_semaphore_obtain

[Johan Zandin]

Sergei Organov  writes:
>"Johan Zandin" <johan.zandin at space.se> writes:
>>        _Context_Switch( &executing->Registers, &heir->Registers );
>>
>>        executing = _Thread_Executing;
>>
>>        _ISR_Disable( level );         -----+
>>                                            |  Region where
>>     }                                      |  an occuring 
>>                                            |  interrupt
>>      _Thread_Dispatch_disable_level = 0;   |  causes problems
>>                                            |
>>      _ISR_Enable( level );            -----+

>But how interrupt can occur when it's disabled in this region?! If
>_ISR_Disable()/_ISR_Enable() don't work on your target, you have hard
>trouble anyway.

The HW interrupt occurs but is left pending until ISRs are enabled,
so the ISR does not execute until somewhere within the _ISR_Enable call
(in the first cycle when ISRs are enabled in the CPU again).

/Johan

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Johan Zandin                      Software Engineer
Saab Space AB                     Phone: +46-31-735 41 47
SE-405 15 Gothenburg, Sweden      Fax:   +46-31-735 40 00
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