[coreboot] Black screen during SeaBIOS boot

awokd awokd at danwin1210.me
Sun Dec 17 22:43:29 CET 2017

On Sun, December 17, 2017 7:54 pm, Daniel K wrote:
> Gave CONFIG_ONBOARD_VGA_IS_PRIMARY=y a try but I ran into the issue you
> warned about where it bricks my system: after the boot sequence, the OS
> only sees the onboard vga and never uses the PCIe video card. Made sure
> by connecting two working monitors.

Sorry, I didn't expect both to stop working!

> Let me step back a bit and try to understand coreboot and VGA.
> According to https://www.coreboot.org/VGA_support :
>> If you run coreboot on a system with on-board graphics, you have to
>> embed a VGA on the top level, enter the file name of your option rom
>> and the PCI ID of the associated graphics device in the form
>> <vendor_id>,<device_id>
> However, from https://www.coreboot.org/Build_HOWTO#VGA_support :
>> On some platforms there's support for native gfx init. A VGA BIOS isn't
>> required.
> And on my board's coreboot page
> https://www.coreboot.org/Board:asus/kgpe-d16#Features :
>> Native GFX Init:	Partial,	Text Mode Only,	Now features proper EDID
>> parsing.
> I assumed this meant I didn't need a vgabios.rom, am I right?
Seems to read that way to me too!

> Or should I be actually including a vgabios.rom for the on-board VGA even
> though I never plan on using it? An even stranger question: should I be
> including a vgabios.rom for the PCIe VGA? This seems unlikely because
> factory BIOSes usually work with new video cards without needing to
> update the BIOS.

PCIe VGA cards have an option ROM (aka blob) in the card's firmware. Most
onboard video devices don't have separate firmware, that's why their blob
is included in the system's firmware. Ordinarily, Seabios will execute
these blobs which then initializes the video cards. However, with this in
your Seabios config, I'm not sure how it handles those:


> Or is the issue that SeaBIOS doesn't work in text-mode-only?
> Maybe I'll give GRUB2 a try, that should work in text-mode-only right?

I'm going to have to defer to the experts.

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