[coreboot] VGA and Graphics

[Zoran Stojsavljevic]

Hello Matt,

Pretty sure there is NO Option ROM, vBIOS and INT10H. Why INTEL for GOP
uses VBT is point of debate. Probably just reduced functionality up to
1280x1024. So they have VBT to support BIOS phase GOP GFX. Only!

But I am also 100% sure neither GOP, neither VBT survives post BIOS phase.
It is out of mind to use VBT for WUXGA, or 1080p, or 4K displays, don't you
agree? The detected GFX I/F are passed to Linux as Run Time info (via HOB).
Then Linux brings from scratch GFX, using its own, modern I/Fs. And ports
appropriate drivers to existing GFX info from HOB.

Zoran

On Tue, Apr 4, 2017 at 11:51 PM, Matt DeVillier <matt.devillier at gmail.com>
wrote:

>
>
> On Tue, Apr 4, 2017 at 2:23 PM, Zoran Stojsavljevic <
> zoran.stojsavljevic at gmail.com> wrote:
>
>> Furthermore, let me tell you all that this is a mechanism to support ONLY
>> The Legacy BIOS (UEFI works ONLY with GOP, but this is another
>> dimension/discussion), and, to all of your knowledge (which I have no idea
>> how deep it is, I doubt), VBT table survives postmortem BIOS. By Linux, it
>> will be RELOCATED into much higher (over 1MB) 32bit protected mode memory
>> (addresses recalculated), and still use INT10H, using vBIOS (Option ROM, my
>> best guess) down there.
>>
>>
> no, the UEFI GOP driver needs the VBT to actually do anything.  Look at
> any current PC UEFI firmware, or even x86 ChromeOS firmware, and you'll see
> they all use/contain a VBT still.
>
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