From: Chris Wilson <chris@chris-wilson.co.uk>
To: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org,
David Weinehall <david.weinehall@intel.com>
Subject: Re: [PATCH] drm/i915: Fill unused GGTT with scratch pages for VT-d
Date: Tue, 12 Jul 2016 09:59:53 +0100 [thread overview]
Message-ID: <20160712085953.GM6157@nuc-i3427.alporthouse.com> (raw)
In-Reply-To: <1468313426.5866.1.camel@linux.intel.com>
On Tue, Jul 12, 2016 at 11:50:26AM +0300, Joonas Lahtinen wrote:
> On pe, 2016-06-24 at 14:07 +0100, Chris Wilson wrote:
> > One of the numerous VT-d workarounds we require is that the display
> > hardware reads past the end of the buffer triggering VT-d faults. This
> > is acknowledged in the code as being safe "since we fill the unused
> > portions of the GGTT with the scratch page". Alas, that is no longer
> > always true and so we trigger DMAR read faults.
> >
> > Skylake also requires another workaround to avoid mixing VT-d and
> > unpopulated PTE, and so there we also need to ensure we fill unused
> > entries with the scratch page.
>
> Rather agressive W/A for just scanout, so maybe drop the scanout word?
The original w/a was just for VT'd + scanout, I was thinking of a
comment, but it never materialised.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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prev parent reply other threads:[~2016-07-12 9:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-24 13:07 [PATCH] drm/i915: Fill unused GGTT with scratch pages for VT-d Chris Wilson
2016-06-24 14:47 ` ✓ Ro.CI.BAT: success for " Patchwork
2016-07-08 12:02 ` [PATCH] " Chris Wilson
2016-07-08 12:29 ` David Weinehall
2016-07-08 12:39 ` Chris Wilson
2016-07-12 8:50 ` Joonas Lahtinen
2016-07-12 8:59 ` Chris Wilson [this message]
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