[coreboot] VGA and Graphics

[Zoran Stojsavljevic]

You see, Nico, you implicitly answered to Ron's quest to make Coreboot
vBIOS/GOP WiKi page... :-)

> Maybe this helps you to untangle this: When the VBT was invented, it
> might have been named after Intel's Video BIOS because that was its
> first consumer. However the name is or has become unrelated to its func
tion.
> If somebody would come up with a name for the VBT, looking at what
> it is today, he might call it *Intel Graphics Driver Configuration Table*
> (IGDT). The acronym IGDT looks much different from VBE, no temptation
> to see them related. Also, why should GOP replace IGDT and reinvent how
> Intel develops its graphics drivers? GOP is just about pre-OS environ-
> ments (cross-vendor), while IGDT is common to all of Intel's graphics
drivers.

Nico/Matt,

You two (as a team) are the best candidates to make this Coreboot WiKi page.

It will have Thermonuclear Hit/Influence on the Open Net and Open Source. I
do agree on name:
*Intel Graphics Driver Configuration Table (IGDCT). Instead VBT!*

I'll tell to you: INTEL (devil) himself will consider to change VBT name to
what you have proposed. :-)

Does it sound reasonable?! ;-)

Thank you for understanding,
Zoran

On Wed, Apr 5, 2017 at 7:54 PM, Nico Huber <nico.h at gmx.de> wrote:

> On 05.04.2017 17:03, Zoran Stojsavljevic wrote:
> > To Coreboot,
> >
> > http://www.uefi.org/sites/default/files/resources/
> UPFS11_P4_UEFI_GOP_AMD.pdf
> >
> > Please, read about GOP, and what GOP suppose to be.
> >
> > So, GOP actually need to replace vBIOS, VBT, legacy INT 10H, and complete
> > VBE 3.0 standard. Why (I have no idea what INTEL does with GOP and how it
> > implements it) it is not done in this fashion...?! At least this is my
> > impression how this should be done.
>
> no, no, no, no. Since VBT is not related to the concept of a Video BIOS
> or any standard (how many people does it need to convince you? :-), it
> cannot be replaced by something (GOP) that continues this standards
> story.
>
> Maybe this helps you to untangle this: When the VBT was invented, it
> might have been named after Intel's Video BIOS because that was its
> first consumer. However the name is or has become unrelated to its func-
> tion. If somebody would come up with a name for the VBT, looking at what
> it is today, he might call it Intel Graphics Driver Configuration Table
> (IGDT). The acronym IGDT looks much different from VBE, no temptation
> to see them related. Also, why should GOP replace IGDT and reinvent how
> Intel develops its graphics drivers? GOP is just about pre-OS environ-
> ments (cross-vendor), while IGDT is common to all of Intel's graphics
> drivers.
>
> From another perspective: IGDT contains proprietary settings for Intel
> silicon, close to register level. VBE is, at its core, about high-level
> framebuffer (data in RAM) formats.
>
> Nico
>
> >
> > I'll continue to investigate.
> >
> > Thank you,
> > Zoran
> >
> > On Wed, Apr 5, 2017 at 4:54 PM, Matt DeVillier <matt.devillier at gmail.com
> >
> > wrote:
> >
> >> On Tue, Apr 4, 2017 at 10:12 PM, Zoran Stojsavljevic <zoran.
> >> stojsavljevic at gmail.com> wrote:
> >>
> >>> 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!
> >>>
> >>
> >> From what I can tell, it's mainly used to provide the output connector
> >> types/mapping to the GOP driver, as well as level shifting etc.
> >>
> >>
> >>>
> >>> 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.
> >>>
> >>
> >> The VBT data is used by both the Linux and Windows display drivers (via
> >> the OpRegion ACPI structure), and the latter will give you a nice black
> >> screen if your VBT is missing or incorrectly configured.  As I noted
> above,
> >> it appears to be used more for output/pipe info than display modes
> (which
> >> are all generated from EDID, outside of standard VESA/CEA ones)
> >>
> >> On Tue, Apr 4, 2017 at 10:12 PM, Zoran Stojsavljevic <
> >> zoran.stojsavljevic at gmail.com> wrote:
> >>
> >>> 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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