[coreboot] Porting to Asus M4A78-EM

Juhana Helovuo juhe at iki.fi
Sat Dec 4 18:12:43 CET 2010

Myles Watson 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>

Oh, this was very good! Thank you! Now I can load Linux kernel on the 
M4A78-EM, although it doesn't boot successfully yet.

The boot is via Coreboot -> SeaBIOS -> Grub2 (Debian default) from SATA 
-> Linux from SATA disk.

Linux boot seems to proceed otherwise nicely, except that it has 
problems initializing SATA and USB controllers on the SB700. IDE works 
better, as it can at least identify the CD drive model. ACPI does not 
work either. The boot log is attached.

At least USB is complaining about missing interrupts. Perhaps that is 
also the case with SATA.

I'll have to do some more testing to find out more.

Best regards,
Juhana Helovuo
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