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

Kevin O'Connor kevin at koconnor.net
Fri May 30 01:56:53 CEST 2008

Hi Myles,

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.

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.


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