Re: [PATCH v2] vfio: Add property documentation

["Corvin Köhne" <corvin.koehne@gmail.com>]

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On Thu, 2025-02-13 at 14:45 -0700, Alex Williamson wrote:
> On Thu, 13 Feb 2025 14:50:50 +0100
> Cédric Le Goater <clg@redhat.com> wrote:
> > +    /*
> > +     * IGD
> > +     */
> > +
> > +    object_class_property_set_description(klass, /* 2.7 */
> > +                                          "x-igd-opregion",
> > +                                          "Add IGD OpRegion support for
> > (headless system)");
> 
> [Cc Tomita and Corvin have more recent understanding of IGD options]
> 
> Not necessarily for headless systems, unless others have better
> suggestions, maybe just "Expose host IGD OpRegion table to guest".
> 

Sounds good. Note that it's required for the Intel GOP (EFI driver) and the
Windows driver. So, it's mandatory for non headless systems.

> > +    object_class_property_set_description(klass, /* 2.7 (See c4c45e943e51)
> > */
> > +                                          "x-igd-gms",
> > +                                          "Add Intel graphics legacy mode
> > device assignment support. "
> > +                                          "Assign 00:02.0 from the host to
> > 00:02.0 in the VM");
> 
> Not really.  Tomita added a useful comment and commit log in
> 37f05a59e869.  Perhaps:
> 
> "Override DVMT Pre-Allocated value for IGD stolen memory. (32MiB units)"

Nit: This sets the Graphics Mode Select value of the GMCH Graphics Control
register. While we currently only support values in the range of 0x00 - 0x40, I
don't see a reason to not support 0xF0 - 0xFE which uses 4 MiB increments.


-- 
Kind regards,
Corvin

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