rtems_semaphore_obtain problems identified

Johan Zandin johan.zandin at space.se
Wed May 2 09:14:20 UTC 2007

Regarding the rtems_semaphore_obtain discussion, I just want
to inform everyone that the two RTEMS bugs 1237 and 1241 have
been raised and that fixes for those are available from OAR.
Fixing these bugs solved our semaphore problems, and hopefully
it will work for others as well.

Just a short summary of the bugs:
(see http://www.rtems.org/bugzilla for more details)

* RTEMS bug 1237 exists in all RTEMS versions and probably
  on most platforms. It is related to interrupts occuring
  during task switches and the symptoms are that stacks
  may grow too large, overwriting other memory areas.

* RTEMS bug 1241 only exists in CVS since sometime in March
  and not in any official RTEMS version from OAR. It is
  related to semaphore signaling during task priority 
  changes (due to priority inheritance). The symptoms are
  that tasks will be kept waiting forever for a semaphore
  (even if they have a timeout).

Best regards
/Johan Zandin

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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