[U-Boot] [coreboot] U-Boot-x86 / coreboot Integration

[Graeme Russ]

On Wed, May 11, 2011 at 10:46 AM, Peter Stuge <peter at stuge.se> wrote:
> Graeme Russ wrote:
>> >> 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?
>
> That depends completely on the particular VGA option ROM.
>
> Having as complete a BIOS environment as can possibly be accomplished
> is the only hope to making arbitrary option ROMs work.
>
> Option ROMs are heavily tied into the BIOS concept.
>
>
>> (surely not all the IDE and keyboard stuff for example)
>
> I think I've seen some VGA option ROM get stuck waiting for
> non-working keyboard BIOS services.
>
>
>> - Could the bare minimum be implemented in a stripped-down modified
>> SeaBIOS?
>
> Not really.
>
>
>> All this because stupid hardware manufacturers refuse to release details
>> of how to do even the most basic of functions with their hardware :(
>
> Welcome to coreboot.

OK, well maybe the coreboot/u-boot scenarion goes like this:

1) coreboot initialises SDRAM and other 'critical' hardware
2) coreboot launches a U-Boot payload
3) If U-Boot does not care about console output then move on and boot
   the OS
4) If U-Boot has a driver for the video hardware then use it for console
   output
5) If U-Boot does not have a driver then load SeaBIOS (modified a bit) and
   the VGA option ROM and use BIOS calls for console output

horrid, horrid, horrid

Regards,

Graeme