[coreboot] Fwd: POST cards, I/O ports and M.2 to MiniPCIe

Trammell Hudson hudson at trmm.net
Tue Apr 3 23:29:55 CEST 2018

On Tue, Apr 03, 2018 at 06:32:07PM +0300, Kyösti Mälkki wrote:
> [...]
> > I'm dealing an early bring-up problem on a modern architecture without
> > serial ports and wondering if that would a good way to debug it.
> Probably M.2 is not very useful for you... try to look for LPC
> signals, some boards have TPM add-on connector with the required
> signals for POST display.

That's a good idea, although on this board the TPM is very hard to
get to, which is nice for moderate physical security, but not great
for debugging.  I'm bummed that the LPC lines aren't brought out to
the M.2 and MiniPCIe; perhaps I'll find an alternate use of the boards
when they arrive.

What ended up working for me was the PC speaker since there is no other
I/O available so early.  I'd really like to thank Uwe Hermann and the
other devs of libpayload/speaker.c -- I was able to port their driver
functions to execute very soon after the reset vector and confirm code
execution with beeps and busy waiting.


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