> Would Linux block my ability to manually probe these i/o ports? Not beyond reserving the region which you've said you've covered. What you may want to try is making sure Linux doesn't program the DMA controller (in case its doing something which disables the port in poking at it). Beyond that I guess ask the manufacturer for info. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html