Re: [PATCH 2/2] x86: add early quirk for reserving Intel graphicsstolen memory v3

From: Jesse Barnes
Date: Fri Jul 26 2013 - 13:12:25 EST

On Fri, 26 Jul 2013 09:58:45 -0700
"H. Peter Anvin" <hpa@xxxxxxxxx> wrote:

> On 07/25/2013 09:37 AM, Jesse Barnes wrote:
> > Systems with Intel graphics controllers set aside memory exclusively for
> > + /*
> > + * Almost universally we can find the Graphics Base of Stolen Memory
> > + * at offset 0x5c in the igfx configuration space. On a few (desktop)
> > + * machines this is also mirrored in the bridge device at different
> > + * locations, or in the MCHBAR.
> > + */
> This comment makes me nervous. It isn't clear to me if it is saying:
> - All igfx devices has the graphics base at 0x5c, a few have it in
> other places, too (which doesn't matter, we can use 0x5c anyway), or
> - Most igfx devices have the graphics base at 0x5c, some don't, and we
> hope and pray we're not on one of those systems because we're not
> checking.
> I assume it is the former, but it really needs to be phrased better.

I mostly copied it from the driver where we had some other ways of
finding it too. For the PCI IDs listed, we can always use 0x5c. I'll
fix the comment.

Jesse Barnes, Intel Open Source Technology Center
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