This change fixes the problem for all the cases we actively use. If you want to try
more creative I/O device attachments (E.g. sharing an L2), this won't work. You
would need another level of caching between the I/O device and the cache
(which you actually need anyway with our current code to make sure writes
propagate). This is required so that you can mark the cache in between as
top level and it won't try to send ownership of a block to the I/O device.
Asserts have been added that should catch any issues.
makeArmSystem creates both bare-metal and Linux systems more cleanly.
machine_type was never optional though listed as an optional argument; a system
such as "RealView_PBX" must now be explicitly specified. Now that it is a
required argument, the placement of the arguments has changed slightly
requiring some changes to calls that create ARM systems.
This makes sure that the address ranges requested for caches and uncached ports
don't conflict with each other, and that accesses which are always uncached
(message signaled interrupts for instance) don't waste time passing through
caches.
