[coreboot] U-Boot-x86 / coreboot Integration

Graeme Russ graeme.russ at gmail.com
Wed May 11 02:40:23 CEST 2011

Hi Kevin

On Wed, May 11, 2011 at 10:23 AM, Kevin O'Connor <kevin at koconnor.net> wrote:
> 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.

I don't see why - I'm sure U-Boot could launch it in exactly the same way
coreboot does... Oh, I see - It will then start trying to boot the system
oops ;)

>> > 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).

How many functions are needed? (surely not all the IDE and keyboard stuff
for example) - Could the bare minimum be implemented in a stripped-down
modified SeaBIOS?

All this because stupid hardware manufacturers refuse to release details
of how to do even the most basic of functions with their hardware :(



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