Avoid interpreting the upper 32 bits of 64-bit BARs as a 32-bit BAR.
Otherwise, the code would assume that the value 0 was incorrect and either:
(a) [on bus 0] "fix up" the address to some nonzero value, thus placing
the decoded address range outside of 32-bit address space, or
(b) [elsewhere] completely disable the device.
The fact that this behaviour depends on the bus number of the device is
already XXX'd.
XXX: This will need revisiting if and when we ever want to handle a PCI bus
XXX: with more than 32 bits of address space on an i386.
The onboard Adaptec 7890 on my Dell Precision Workstation 410 works again.
fvdl