[coreboot] Porting to Asus M4A78-EM

Myles Watson mylesgw at gmail.com
Tue Dec 7 20:36:54 CET 2010

On Tue, Dec 7, 2010 at 8:44 AM, Scott Duplichan <scott at notabs.org> wrote:
> On Thu, Dec 2, 2010 at 9:17 AM, Myles Watson <mylesgw at gmail.com> wrote:
>>> "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
>> I don't see any reason not to move that resource into the northbridge
>> to avoid that issue.  It's a simple fix.  Is there a good reason for
>> having the MMCONF BAR in the APIC cluster?
> This is what I was thinking.  Build tested only.
> Signed-off-by: Myles Watson <mylesgw at gmail.com>
> Thanks,
> Myles
> Thanks for this patch Myles.
> Acked-by: Scott Duplichan <scott at notabs.org>
Rev 6148.

I think that some nice next steps would be:

- Set the size of the MMCONF area based on the number of busses in the machine.
- Let the resource allocator assign the location so that it doesn't
waste address space.

I don't think it would be too difficult, but it would require some testing.


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