[coreboot] Question about Intel HD graphics and FLR

[Zoran Stojsavljevic]

Joshua,

(did you ever watch some James Bond movie with idiom: "if I tell you, then
I must kill you?) 👻

> AFAIK, Windows doesn't need a virgin state but the state the VBIOS / GOP
> driver usually leaves the hardware in. Plus a Video BIOS Table (VBT)
> with some hints about a board's specifics. What are these older boards?
> Are you sure they support FLR? The first hints about FLR support I could
> find were is a Haswell datasheet.

It appears/shows to me from the Other Side of the Wall that Nico might be
(somehow) correct. But I need to do verification on that as well.

Please, stay tuned (hopefully)!

Zoran

On Thu, Mar 30, 2017 at 8:36 PM, Nico Huber <nico.h at gmx.de> wrote:

> Hi JP,
>
> On 30.03.2017 17:48, Joshua Pincus wrote:
> > Hi Zoran,
> >
> > Thanks for your reply.
> >
> > My situation is this: When the VM guest comes up the first time from a
> > system-level reset (aka power on), the Broadwell HD graphics device runs
> > fine.  I see basic VGA both before and during the boot of Windows.  Once
> > Windows boots, the HD graphics device is configured by Intel's driver
> and I
> > see hi-rez output.  On a reboot of Windows within the VM, an FLR is
> > issued.  When the guest comes back up, no VGA.  Windows does boot but
> > provides no VGA output.  If Windows needs to drop into VGA mode so that a
> > user can access the real-mode functionality of the recovery console,
> still
> > no VGA.
>
> what kind of VM? what does it usually do when booting to support windows
> (supposedly runs some BIOS / UEFI code)? Does that include running a
> VBIOS or GOP UEFI driver?
>
> >
> > It's only on Broadwell-based boards that we have this problem.  If we
> issue
> > FLRs during the reset of the PCI bus for older Intel boards, no problem.
> > We get VGA.  Something involved with the FLR is messing up the state of
> the
> > hardware instead of actually returning the hardware to a virgin state,
> akin
> > to what you would get from a full system reset.
>
> AFAIK, Windows doesn't need a virgin state but the state the VBIOS / GOP
> driver usually leaves the hardware in. Plus a Video BIOS Table (VBT)
> with some hints about a board's specifics. What are these older boards?
> Are you sure they support FLR? The first hints about FLR support I could
> find were is a Haswell datasheet.
>
> Nico
>
>
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