Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Some code churn:
o Eliminate IA64_PHYS_TO_RR6 and change all places where the macro is used
by calling either bus_space_map() or pmap_mapdev().
o Implement bus_space_map() in terms of pmap_mapdev() and implement
bus_space_unmap() in terms of pmap_unmapdev().
o Have ia64_pib hold the uncached virtual address of the processor interrupt
block throughout the kernel's life and access the elements of the PIB
through this structure pointer.

This is a non-functional change with the exception of using ia64_ld1() and
ia64_st8() to write to the PIB. We were still using assignments, for which
the compiler generates semaphore reads -- which cause undefined behaviour
for uncacheable memory. Note also that the memory barriers in ipi_send() are
critical for proper functioning.

With all the mapping of uncached memory done by pmap_mapdev(), we can keep
track of the translations and wire them in the CPU. This then eliminates
the need to reserve a whole region for uncached I/O and it eliminates
translation traps for device I/O accesses.

Revamp bus_space access functions:
o Optimize for memory mapped I/O by making all I/O port acceses function
calls and marking the test for the IA64_BUS_SPACE_IO tag with
__predict_false(). Implement the I/O port access functions in a new
file, called bus_machdep.c.
o Change the bus_space_handle_t for memory mapped I/O to the virtual
address rather than the physical address. This eliminates the PA->VA
translation for every I/O access. The handle for I/O port access is
still the port number.
o Move inb(), outb(), inw(), outw(), inl(), outl(), and their string
variants from cpufunc.h and define them in bus.h. On ia64 these are
not CPU functions at all. In bus.h they are merely aliases for the
new I/O port access functions defined in bus_machdep.h.
o Handle the ACPI resource bug in nexus_set_resource(). There we can
do it once so that we don't have to worry about it whenever we need
to write to an I/O port that is really a memory mapped address.

The upshot of this change is that the KBI is better defined and that I/O
port access always involves a function call, allowing us to change the
actual implementation without breaking the KBI. For memory mapped I/O the
virtual address is abstracted, so that we can change the VA->PA mapping
in the kernel without causing an KBI breakage. The exception at this time
is for bus_space_map() and bus_space_unmap().

MFC after: 1 week.