Hi list,
On Thu, Oct 15, 2020 at 5:48 PM Clay Daniels clay.daniels.jr@gmail.com wrote:
Paul, you are probably way ahead of this, but I found something pre-AGESA from 2003 that says:
"Unlike minicomputer systems, the IBM PC was not designed to use a serial console. This has two consequences.
Firstly, Power On Self-Test messages and Basic Input/Output System (BIOS) messages are sent to the screen and received from the keyboard. This makes it difficult to use the serial port to reconfigure the BIOS and impossible to see Power On Self-Test errors.
An increasing number of manufacturers of rackable server equipment are altering their BIOSs to optionally use the RS-232 port for BIOS configuration and test messages. If you are buying a machine specifically for use with serial console you should seek this feature. If you have an existing machine that definitely requires access to the BIOS from the serial port then there are hardware solutions such as PC Weasel 2000.
Secondly, the RS-232 port on the IBM PC is designed for connecting to a modem. Thus a null modem cable is needed when connecting the PC's serial port to a terminal."
https://tldp.org/HOWTO/Remote-Serial-Console-HOWTO/intro-why.html
How does any of this apply to coreboot?
Clay
On Thu, Oct 15, 2020 at 3:54 AM Paul Menzel pmenzel@molgen.mpg.de wrote:
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.cover 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`?
I don't know if AGESA is compiled into a different stage, which would be called `libagesa`. I've just seen some mentions of this in the coreboot code. I suspect logging there might need to be handled differently (similar to how we handle logging in SMM, which is disabled by default).
I'd be surprised if any of the IDS stuff still builds fine. No one bothered to migrate the IDS controls in OptionsIds.h to Kconfig. Should you want to do so, please add various config files in configs/ to ensure the IDS code gets build-tested.
Kind regards,
Paul
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Best regards, Angel