[coreboot] VGA ROM run on v2 Qemu and in legacybios

Myles Watson mylesgw at gmail.com
Fri May 30 13:40:09 CEST 2008

Hi Kevin,

> On Wed, May 28, 2008 at 03:29:14PM -0600, Myles Watson wrote:
> > I was trying to track some things down and noticed that:
> >
> > 1. legacybios runs the VGA ROM even though Coreboot runs it.
> I don't think it is an issue to re-run the vga option rom.  I think
> hitting ctrl+alt+delete effectively re-runs the vga option rom.  So, I
> would think all the vga vendors would make sure re-running was not a
> problem.  Of course, it still increases boot time.
> >     I think that legacybios should only run option ROMs if it is not
> > running as a payload.  Otherwise the ROM gets run twice.
> This isn't so simple.  Running the option rom does two things - it
> inits the card, and it sets up the 16bit vga handlers.  Coreboot can
> init the card, but it isn't designed to fully register the card for
> 16bit apps.

What is it missing?

> So, one can easily disable vga option rom execution in legacybios
> (comment out the first call to rom_scan in post.c), but I don't think
> it will do what you want it to do.
> It should be possible to disable calling the option rom from
> coreboot, however.

That's an interesting problem if you want to have multiple payloads, I guess
you're saying that you run the VGA ROM based on which payload you'll
eventually select?

> -Kevin

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