On Wed, 05 Mar 2014, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Wed, Mar 05, 2014 at 03:32:54PM +0000, Chris Wilson wrote: >> On Wed, Mar 05, 2014 at 04:17:17PM +0100, Daniel Vetter wrote: >> > On Fri, Feb 28, 2014 at 12:14:02PM +0000, Chris Wilson wrote: >> > > We have reports of heavy screen corruption if we try to use the stolen >> > > memory reserved by the BIOS whilst the DMA-Remapper is active. This >> > > quirk may be only specific to a few machines or BIOSes, but first lets >> > > apply the big hammer and always disable use of stolen memory when DMAR >> > > is active. >> > > >> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=68535 >> > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> >> > > --- >> > > drivers/gpu/drm/i915/i915_gem_stolen.c | 14 ++++++++++++++ >> > > 1 file changed, 14 insertions(+) >> > > >> > > diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c >> > > index 984ada1b0084..13a849afe479 100644 >> > > --- a/drivers/gpu/drm/i915/i915_gem_stolen.c >> > > +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c >> > > @@ -325,11 +325,25 @@ void i915_gem_cleanup_stolen(struct drm_device *dev) >> > > drm_mm_takedown(&dev_priv->mm.stolen); >> > > } >> > > >> > > +static bool need_dmar_wa(struct drm_device *dev) >> > > +{ >> > > +#ifdef CONFIG_INTEL_IOMMU >> > > + if (INTEL_INFO(dev)->gen >= 6 && intel_iommu_gfx_mapped) >> > >> > Why the gen check in here? Without that we could just check >> > intel_iommu_gfx_mapped and shovel the #ifdef into stolen init. No need to >> > spread it out like that imo. >> >> It's almost as if it was cut'n'paste from another VTd w/a. I'm worried >> that this is too big a hammer. I would have expected more complaints if >> VTd was this broken since 3.9. Otoh, it is a severe bug. > > We've had piles of bugs in our stolen detection, combined with very few > people having vt-d capable machines (thanks to intel's differentation) and > probably even fewer having it enabled I'm not so much surprised. > > On top of that lots of noise on the interwebz that dmar is trouble for > intel gfx on linux, so people probably just disable it and carry on ... So what's the verdict on this one? BR, Jani. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
