Thanks Andrew,I've tried to load the arinc653 scheduler, however Xen crashes whenever I create a CPU pool with this scheduler. I reported this and it was confirmed by Seeing as I've been fighting to get my little port up, running and communicating via shared pages with a Windows domU I've kind of ignored this. However before I go and invest more time and effort with this I just wanted to confirm that I'm not barking up the wrong tree.Regards.