[coreboot] U-Boot-x86 / coreboot Integration
graeme.russ at gmail.com
Wed May 11 03:05:22 CEST 2011
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
> 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
4) If U-Boot has a driver for the video hardware then use it for console
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
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