[coreboot] Early debugging

[Gergely Kiss]

Hi,

I'm working on porting Coreboot to the ASUS AM1I-A motherboard and I'm a
bit stuck.

I could successfully build Coreboot but after flashing the ROM, my board
looks to be bricked...

Once powering on the board, the CPU fan spins up but then nothing happens,
I can't see any output on the serial console (the connection was tested
prior to flashing by running a getty on the COM port and it was working
fine).

The board is not fried as I can load back the vendor firmware and it boots
up absolutely fine.

I'd like to find out why Coreboot would not start but don't know what tool
would be the most suitable for debugging.

The chipset and the CPU is already supported by Coreboot but the SuperIO
chip is not. It looks to me the serial interfaces of ITE chips work the
same for all models so I believe using the common code for ITE SIO chips
should work but I'm unsure (no datasheet available).

Shall I use a PCIe serial interface card or rather try EHCI debugging? I'm
afraid in case the boot process halts at some early stage (like before
romstage) then I won't see any useful output using any of those.

Using a POST card would be a better approach I think but my board has a
single PCIe 4x slot which seems to be unsupported by POST cards I could
find on the web (except one from a Chinese vendor but it costs about $1k
which is way too expensive).

Here's my WIP code for reference:

https://github.com/kissg1988/coreboot/tree/master/src/mainboard/asus/am1i-a

Any idea how to proceed?

Thanks,
Gergely
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.coreboot.org/pipermail/coreboot/attachments/20171204/f8fcc3c9/attachment.html>