Re: [coreboot] Update AMD Persimmon project to support Windows 7, XP, linux

[Scott Duplichan]

Marc Jones wrote:

]> 1) Work around coreboot resource allocation problem that causes
]> overlap of PCIe MMIO space and graphics MMIO space.
]
]Why isn't this covered by the bus resource allocation for MMCONF? I
]think that this should handle the situation. How does the overlap
]happen?

Hello Marc,

I think the short answer is the mmconf range is added to a device that
is skipped by the bus resource allocation code. The mmconf range is
added to APIC_CLUSTER:0, which is not looked at by the resource
allocation code. Here is what I found a while back:

Why does the current code for handling fixed resources allow the mmconf
  space to get allocated to a PCI device? Function avoid_fixed_resources
  calls function constrain_resources, which recursively searches the
  device tree for fixed io and memory resources. The ioapic fixed memory
  address is found and avoided during the recursive search because this
  southbridge device is below the level where the search starts. On the
  other hand, the mmconf fixed resource is added from the northbridge code,
  and falls under 'APIC_CLUSTER: 0'. This device is not part of the search
  for two reasons. One is that it is not at or below 'pci_domain 0' in the
  device tree. Another reason is that its type is APIC_CLUSTER and not
  PCI_DOMAIN.

The last patch I sent includes a better workaround. To avoid modification
of the resource allocation code, mmconf is moved from e0000000 to f8000000.
This is the solution I attempted originally, but had to set aside until a 
couple of mmio problems were fixed.

Thanks,
Scott