I think that we need to use 'R0' and not 'R1' as it is not set anywhere. It probably doesn't matter much as interrupts should be disabled until the actual interrupt stack is setup latter. This is line 143 of MQX4.0.2 and 139 of MQX-4.1 in boot.S. Is this where I should report issues or is there some SPR system? Am I allowed to show the code lines or does this violate the MQX license?