The alternative weighted scheduler might lead to some threads don't make
any progress anymore (take for example the signal test). So we have to use
the fixed priority scheduler also in the kernel configuration for 64 Bit.
In sigma0 normally no answer tag to a request/fault is created. It simply uses
the message tag received with the request. This doesn't work out when I/O ports
are requested. This patch constructs an appropriate answer tag. Moreover,
we have to enable I/O port protection in the kernel configuration.
