Re: [coreboot] Porting to Asus M4A78-EM

[Myles Watson]

On Tue, Dec 7, 2010 at 8:44 AM, Scott Duplichan  wrote:
> On Thu, Dec 2, 2010 at 9:17 AM, Myles Watson  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
> > > PCI_DOMAIN."
> >
> > 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
>
> Thanks,
> Myles
>
> Thanks for this patch Myles.
> Acked-by: Scott Duplichan

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.

Thanks,
Myles