This has been in my 2.4 BK tree for a while, but I should have
posted it in case there's feedback from other people working
on large machines.  So here it is, in four parts:

  1  enhance __ia64_mk_io_addr(port)
  2  enhance pcibios_scan_root to get multiple mem & io windows
      from ACPI _CRS, and fixup all the resources
  3  add support for /proc/iomem and /proc/ioports
  4  trivial (whitespace, copyright, and move pcibios_fixup_device_resources
       closer to related code)

The current scheme is that IO ports are 64 bits, with the low 24
bits being the port number within an IO port space, and the upper
bits identifying the space.  There is currently a limit of 16
spaces.