[coreboot] SeaBIOS not running vga rom

Joseph Smith joe at settoplinux.org
Wed May 13 03:58:11 CEST 2009

On Tue, 12 May 2009 21:26:04 -0400, Kevin O'Connor <kevin at koconnor.net>
> On Tue, May 12, 2009 at 06:50:26AM -0400, Joseph Smith wrote:
>> This may be a dumb question, but I was wondering, can I use SeaBIOS as a
>> payload without loading assembly blob roms?
>> I ask this because I am going to be running custom VGA code after VM86
>> excicutes the vga rom and returns back to coreboot. I don't think this
>> would be possible for SeaBIOS, because at that point it has already left
>> coreboot. So I would like to just use SeaBIOS as my payload to boot
> disks
>> only. Is this possible? If so what options do I need to define in
> SeaBIOS?
> To turn off option rom processing in SeaBIOS, edit the file
> src/config.h and change the setting CONFIG_OPTIONROMS to 0.
> However, most boot loaders (eg, grub) will require a working vga bios.
> Running the vgabios in an emulator wont register the 16 bit vga
> callbacks - SeaBIOS must run the vgabios in order for these callbacks
> to work.
> It's not clear what your end goal is or what problem you're trying to
> fix - maybe an alternate solution is possible.
Well it would be hard to fit 2 years of research into this email but in a
nut shell I am going to be doing some direct framebuffer manipulation to
get the tv-out working. I need to do this AFTER the VGA ROM runs and sets
up the initial graphics. Therefore the current ROM emulators in coreboot
will let me achieve this because they return to coreboot thus allowing me
to run code directly manipulating the framebuffer. 

I would like to try SeaBIOS but in the above scenario, I don't see how it
is possible.

If you have an alternate solution I am all ears.

Joseph Smith

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