Debugging coreboot in qemu environment - part 1

First of all I use testing version of Debian - wheezy. Clone coreboot repository:

git clone
cd coreboot; make menuconfig

Configure FILO as apayload and use its latest version:

Payload -> Add a payload -> FILO Payload -> FILO version -> HEAD

Add verbose debugging messages:

Debugging -> Check PIRQ table consistency Debugging -> Output verbose malloc debug messages
Debugging -> Output verbose ACPI debug messages Debugging -> Enable debug messages for option ROM execution
Debugging -> Built-in low-level shell Debugging -> Trace function calls

Try to build:


If everything builds correctly you can process. Sometimes there is need to use cross compiler. To build one:

cd util/crossgcc

To explore coreboot code effectively I suggest to create tags and cscope database for coreboot. In my personal workspace I’ve got process that I go through before I start work (if you use my workspace configuration which is available @github you can follow below steps directly, if not adjust to your environment):

  1. run vim ;)
  2. :cd /path/to/code
  3. s<Tab> (fuzzyfinder -> bookmark dir)
  4. si (fuzzyfinder -> change dir)
  5. sr (run ctags to generate tags and cscope to build symbol database - ctags -R;cscope -R -q -b -v)

After steps above we can start work with code. Run vim in coreboot directory. Type: :e src/cpu/x86/16bit/ Put cursor over protected_start and press Ctrl-]. If everything goes ok you should jump to build/mainboard/emulation/qemu-x86/bootblock.s line 537. In second article we dive into first phase of coreboot execution in emulated environment.

Piotr Król
Founder of 3mdeb, a passionate advocate for open-source firmware solutions, driven by a belief in transparency, innovation, and trustworthiness. Every day is a new opportunity to embody the company's vision, emphasizing user liberty, simplicity, and privacy. Beyond business, a casual chess and bridge player, finding peace in nature and nourishment in theology, philosophy, and psychology. A person striving to foster a healthy community, grounded in collaboration and shared growth, while nurturing a lifelong curiosity and a desire to deeply understand the world.