76786b38b6
memory-mapped or i/o-mapped access to the device registers, and always choose memory-mapped if it is enabled. In particular, do _not_ explictly disable the space we decide to not use, as this confuses some versions of Alpha console software (which are arguably buggy because of this problem). Also, fix a logic error pointed out by Ross Harvey <ross@teraflop.com> that would cause memory-mapped access to never be enabled.