[coreboot] Porting to Asus M4A785-M

[Myles Watson]

> Coreboot now boots past the romstage and starts setting up PCI devices.
> Unfortunately, it crashes at some point during PCI setup. I do not have
> access to the boot log right now, but could post it later.
That would be helpful.
 
> I suspect that the devicetree.cb source file is somehow wrong and
> therefore coreboot does some wrong initialization or probe, which causes
> an immediate reboot.
Usually an incorrect device tree wouldn't cause a reboot.  Do the devices
selected in your Kconfig file match the devices in your device tree?
 
> Is there a reference manual for writing the devicetree.cb file? All the
> documents I found in the Coreboot wiki seemed to describe some past
> version of it.
The best thing to do is copy a device tree from a similar board.  The hard
thing about AMD device trees is that the chips in a HyperTransport chain
need to be listed in reverse order.  You'll get a lot more malloc debugging
statements if your device tree is incorrect, since it will find the devices
(just not where it expects to), and the devices from the tree will be
disabled.

> Can the correctness of devicetree.cb be somehow verified against lspci
> output? If so, how?
The best way is looking through the log to see which devices are allocated
with malloc, and which get disabled.

Thanks,
Myles