[coreboot] U-Boot-x86 / coreboot Integration

[Kevin O'Connor]

On Wed, May 11, 2011 at 09:44:00AM +1000, Graeme Russ wrote:
> On Wed, May 11, 2011 at 2:08 AM, Peter Stuge <peter at stuge.se> wrote:
> > Graeme Russ wrote:
> >>  - Do we care about legacy BIOS support (SeaBIOS) for now (I think
> >>    not)?
> >
> > IMO it is not relevant to the integration of coreboot and U-Boot. If
> > a BIOS is needed by U-Boot itself or whatever it loads, then SeaBIOS
> > must be used as payload for coreboot, and SeaBIOS will then start
> > U-Boot after setting up the BIOS environment.
> 
> Or U-Boot could load a SeaBIOS image and initialise it if needed. So
> in a U-Boot script:
>   - If the target OS is GNU/Linux the load the Linux kernel image and go
>   - If the target OS is Windows (or any other OS which needs a BIOS) then
>     U-Boot first loads a SeaBIOS image and then loads the image for the
>     target OS (this may even be a 'GRUB' image for example)

That's possible to do, but would likely require some changes to SeaBIOS.

> > for two or three graphics chipsets. SeaBIOS can initialize any VGA
> > option ROM, but then you need SeaBIOS in the loop.
> > Option ROMs are ageold technology and stupid, but they are still
> > firmly entrenched in PC hardware. A BIOS was always there so everyone
> > assumes it will always stay there, not very many question if
> > something better could be done.
> 
> Would be interesting to investigate implementing a stub in U-Boot to
> initialise and use VGA option ROMs

VGA option ROMs call BIOS functions.  So, one needs a BIOS
implementation (eg, SeaBIOS) or an emulator for them (eg, in
coreboot).

-Kevin