Ok, thanks for your help! I'm sorry for sending this issue to the wrong list, I'm quite new to this and my thought was that is the correct list as the issue was happening with a vanilla kernel too. Just to summarize: - on real HW with rtai-patch the issue is caused by rtai - the vanilla kernel used with vmware has some other issues so the conclusion is that I avoid the use of function tracing for now. Regards Felix PS: what list would have been the right one for this issue? -- To unsubscribe from this list: send the line "unsubscribe linux-trace-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html