[coreboot] disabling Intel iGPU on Skylake/Kaby Lake CPU

[Maxim Poliakov]

Hi all!
I have a problem with disabling the internal Intel GPU in the coreboot for
the Skylake/Kaby Lake processor.
If I understand correctly, in order to disable the iGPU, I must to set
"InternalGfx" to 0 in UPD options for Intel FSP.
https://github.com/coreboot/coreboot/blob/master/src/soc/intel/skylake/romst...

But, in this case, the loading of the coreboot stops after running the
FSP-S in ramstage.

Please see logs: https://drive.yadro.com/s/3ocCtS3EemjyT5f

I ran the coreboot image with iGPU turned off on the following boards:

- Asrock H110M-DVS board (i5-6600 desktop CPU), coreboot:
4.9-1254-gadde497;
 - Intel KBL-R U RVP board (i5-8350u mobile processor), coreboot:
4.9-55-g04a7ce7.
In both cases it doesn`t work.

I think that it is not enough to change only InternalGfx.

Any ideas on this?
Has anyone tested Сhromebooks or other motherboards with Skylake/Kaby Lake
processor when iGPU is turned off?

Thanks.

// Regards,
// Max