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

[Nico Huber]

On 10.04.19 14:31, Maxim Poliakov wrote:
> 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

Last line (would have been easier if you'd have attached it btw.):
> POST: 0x93

This is POST_FSP_SILICON_INIT, so it stops whilst running FSP-S, not
after.
> Any ideas on this?

File a bug at github.com/IntelFsp/FSP. If you have any direct contact to
Intel, ask them for help or a blob with debug output.
> Has anyone tested Сhromebooks or other motherboards with Skylake/Kaby Lake
> processor when iGPU is turned off?

I didn't for my part.

Nico

[Maxim Poliakov]

Hi Nico. Thanks for the help.
I'm still trying to fix this problem.
Unfortunately, I don`t have direct contact to Intel:)
But, I'm not sure what the problem is in the FSP.

After many experiments, I really got to disable iGPU and run coreboot.

This works if we do not use GFXVT resources in the MCHBAR space for
VT-d/VT-x (GFXVTBAR is not programmed).
Thus, "GFXVTBAR" should be removed from the soc_vtd_resources[] when VT-d
is configured in
https://github.com/coreboot/coreboot/blob/master/src/soc/intel/skylake/inclu...

I tested it on VirtualBox (5.1.38_Ubuntur122592) + Ubuntu 18.04.1 as the
guest OS.
3D acceleration works well with the nouveau driver on the host OS.

I think this is very useful if the coreboot will be used on skl/kbl
processors without integrated graphics.

Can I add this as a patch to upstream?

There is another issue regarding vmx:
The legacy initialization code for vmx is located in the
src/soc/intel/common/block/vmx directory.
This code has an "undefined reference to soc_fill_vmx_param".
In addition, the line "Enable VMX for virtualization" in the menu is
duplicated.
Instead, the code in src/cpu/intel/common/common_init.c is now used.
https://review.coreboot.org/c/coreboot/+/29682

Can I remove legacy code?

Thanks!

// Regards,
// Max

ср, 10 апр. 2019 г. в 20:36, Nico Huber :
> On 10.04.19 14:31, Maxim Poliakov wrote:
> > 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
>
> Last line (would have been easier if you'd have attached it btw.):
> > POST: 0x93
>
> This is POST_FSP_SILICON_INIT, so it stops whilst running FSP-S, not
> after.
> > Any ideas on this?
>
> File a bug at github.com/IntelFsp/FSP. If you have any direct contact to
> Intel, ask them for help or a blob with debug output.
> > Has anyone tested Сhromebooks or other motherboards with Skylake/Kaby
>
> Lake
> > processor when iGPU is turned off?
>
> I didn't for my part.
>
> Nico