[ECOS] DSR interruptible by scheduler + memory barriers

Martin Laabs martin.laabs@mailbox.tu-dresden.de
Tue May 22 18:01:00 GMT 2012


Hello,

unfortunately I couldn't find the answer in the documentation. If the 
scheduler runs a DSR. Can this DSR become interrupted by an other thread or 
another DSR? (Of cause an ISR can interrupt it)

The background is that I wanna share data between a thread an a DSR and 
want to know whether I have to call cyg_(un)lock_scheduler when changing 
the data.

And another question about that - how are memory barriers implemented in 
eCos? (Are they implemented at all?)
Background: I have - for example - a status bit field that is copied to a 
(ISR/DSR) shared variable in the ISR. Now - if the compiler decides to put 
this variable into a register (in the ISR function) the DSR will get the 
wrong data. I could of cause declare the variable as volatile but this 
might be a performance issue in other cases where more data is affected.

Best regards,
  Martin Laabs


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