How to debug open-source AGESA with serial console?

[Paul Menzel]

Dear coreboot folks,

To get PCI bridge 0:15.2 enabled for the network device on the Asus 
F2A85-M PRO, I want to debug the PCIe General Purpose Ports lane 
configuration of the FCH.

I’d like to print some variables in

src/vendorcode/amd/agesa/f15tn/Proc/Fch/Pcie/GppPortInit.c

over the serial console. It looks like

#include <console/console.h>

and `printk(BIOS_DEBUG, …)` compiles, but the messages are not sent over 
serial console. Is that expected?

Do I need to use AGESA’s Integrated Debug Services (IDS) [1], and enable 
the console in `src/mainboard/asus/f2a85-m/OptionsIds.h`?

Kind regards,

Paul

[1]: 
https://www.coreboot.org/images/3/36/AGESA_Interface_Spec_for_Arch_2008_v3.0...