[coreboot] VGA and Graphics

[Patrick Rudolph]

VBT is documented by intel-gpu-tools. There's intel_vbt_decode (former intel_bios_decode) available https://cgit.freedesktop.org/xorg/app/intel-gpu-tools/tree/tools/intel_vbt_decode.c that will print all tables in human readable form.
Regards Patrick

Am 4. April 2017 20:45:15 MESZ schrieb Nico Huber <nico.h at gmx.de>:
>Hi Ron,
>
>On 04.04.2017 19:46, ron minnich wrote:
>> Igor, if you are going to say things like "AFAIK there is no public
>> description of these tables' layout and contents, only Intel knows
>how to
>> build and parse them.", it's really a good idea to back it up with a
>> primary source, especially since you also use phrases like "I assume"
>and
>> "I guess". I am pretty sure you're wrong in this case. The V in VBT,
>as I
>> understand it, means VESA, and VESA has been a standard for about 30
>years.
>> 
>> Please, everyone, if you're going to move this conversation forward,
>you
>> need to cite primary sources at least, such as this one:
>> http://www.petesqbsite.com/sections/tutorials/tuts/vbe3.pdf.
>
>now you got confused too. I'll try to clarify.
>
>VBE means VESA (Video Electronics Standards Association) BIOS
>Extension.
>It's a Video BIOS interface extension (i.e. specifying additional BIOS
>calls). Don't know if it was public from the beginning (you often have
>to be a VESA member to get access to their "standards"), but the inter-
>face is used by many open source programs. It's vendor independent.
>Also
>it's off-topic, nobody was discussing it here.
>
>As Igor noted, VBE has absolutely nothing to do with VBT.
>
>VBT means Video BIOS Table. It's a 100% Intel specific table of confi-
>guration options for Intel's Video BIOS and Intel's graphics drivers.
>There is no public documentation, but as it's used by the Linux driver,
>at least the structure and some of the values are publicly "documented"
>[1]. Developers of the i915 Linux driver stated that they are not wil-
>ling to support systems without a VBT. Most features of the i915 driver
>work without a VBT by chance. But anything board specific, like inte-
>grated panels in laptops, will likely _not_ work. I'd also expect that
>they won't count it as a regression if something breaks but would still
>work with a VBT. (Windows won't even try to get things running without
>VBT, AFAIK.)
>
>An OEM should have access to Intel's binary configuration tool and the
>specification file for the VBT of his processor's generation. It comes
>along with the VBIOS, I suppose.
>
>Nico
>
>PS. Igor, Zoran please write text-only emails or at least make sure the
>    text version is readable and quotes are visible as quotes.
>
>[1]
>https://www.kernel.org/doc/html/latest/gpu/i915.html#video-bios-table-vbt
>
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