For older systems with ACPI which don't have a pci <-> pci bridge,

For older systems with ACPI which don't have a pci <-> pci bridge,
allocate unallocated memory resources from the top 32MB of the address
space rather than the top 2GB.  While the latter works on some
chipsets, it fails badly on others.  32MB is more conservative and
matches what cheap harware from this era is hardwired to pass.