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

[Graeme Russ]

On Wed, May 11, 2011 at 1:20 PM, Kevin O'Connor <kevin at koconnor.net> wrote:
> On Wed, May 11, 2011 at 01:12:16PM +1000, Graeme Russ wrote:
>> >> > 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).
>>
>> What does Linux do? i.e. if you boot Linux from coreboot, how does it
>> output to the VGA console? I know it uses BIOS early on (before switching
>> to protected mode) but what does it do after entering protected mode?
>
> In general, one enables the coreboot VGA option ROM emulation when
> booting Linux directly from coreboot.
>

Yes, I understand that - But how does Linux output to the VGA console
after switching to Protected Mode? Does it still do BIOS calls?

And what about all those Linux drivers in drivers/video - Would porting
them (to U-Boot) elliminate the need for BIOS/Option ROMs

Note: Please pardon my ignorance if these appear to be dumb questions - I
really don't know how the guts of VGA console works

Regards,

Graeme