RTEMS ISR question - management of the ET PSR-bit on ERC32

Matthew McBraida Matthew.McBraida at scisys.co.uk
Thu Mar 10 17:03:50 UTC 2011



I have a question about interrupt handling with RTEMS/ERC32: 


I understand from TSC691E Users manual issue I, sections 3.7.17 / 3.8.5
/ that: a trap causes the processor to clear ET; a synchronous
trap when ET=0 results in an error condition that forces a reset; and
that RETT automatically sets ET back to 1.   

Am I right to believe that the RTEMS generic ISR "_ISR_Handler()" sets
ET to 1 just before calling the user-trap-handler, and then clears it
again just after it returns?  

I guess that the end result of all this is that normally for most of the
processing time of a trap handler, a synch trap occurring will not
result in a processor error...


(I refer to the TSC691E Users manual instead of the TSC695F manual due
to the far greater detail given in the former).  





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