[coreboot] VGA and Graphics

[Arthur Heymans]

Igor Skochinsky via coreboot <coreboot at coreboot.org> writes:

> Hello Patrick,
>
> Tuesday, April 4, 2017, 8:54:09 PM, you wrote:
>
> PR> VBT is documented by intel-gpu-tools. There's intel_vbt_decode
> PR> (former intel_bios_decode) available
> PR> https://cgit.freedesktop.org/xorg/app/intel-gpu-tools/tree/tools/intel_vbt_decode.c
> PR> that will print all tables in human readable form.
>
> Nice find! I did not realize this tool supports that many structures;
> for some reason I thought it just prints some general info without details.
>
> So now that we have a dumper the following should be possible:
> 1) make a "decompiler" that would convert VBT from the option ROM into a human/machine
> readable text format
> 2) make a "compiler" that would take that text format and create a
> binary VBT from it
> 3) put the binary VBT into the ACPI IGD OpRegion table ([1], [2]), or
> wherever the graphics driver can find it.
>

I think blobtool would fit that purpose quite nicely on the assumption
VBT is already extracted and that VBT has fixed locations for its
entries.  If one writes a blobtool spec file (which describes the
bitfields) it can serve both as a "decompiler" and as a "compiler".

>So, basically, an approach similar to ich9gen for the flash
>descriptor/gbe.

Blobtool handles ICH9 IFD and GBE compilation and decompilation too. ;)

>This should allow getting rid of the option ROM if real mode support is
>not required.

Would great to have indeed, who knows if other OS drivers will mandate
VBT one day.


Kind regards.
-- 
Arthur Heymans