Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v2 4/6] iommu/vt-d: Remove 1:1 mappings from identity domain | Date | Wed, 13 Dec 2023 02:20:10 +0000 |
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> From: Baolu Lu <baolu.lu@linux.intel.com> > Sent: Tuesday, December 12, 2023 2:21 PM > > > > For GFX it's a workaround added since day one. there is even still > > an option CONFIG_INTEL_IOMMU_BROKEN_GFX_WA available. But > > now its meaning is really disabling IOMMU instead of using identity. > > > > sounds like IDENTMAP_GFX can be fully removed now: > > > > #ifdef CONFIG_INTEL_IOMMU_BROKEN_GFX_WA > > dmar_map_gfx = 0; > > #endif > > We should already remove the workaround for the 2.6 kernel. :-)
I don't know what happened to ignore that temporary option.
> > It's default "n". Therefore, if any gfx driver still needs this > workaround, there should already be a bug report.
It depends on how it is set in distros.
> > > > > if (!dmar_map_gfx) > > iommu_identity_mapping |= IDENTMAP_GFX; > > So with above cleaned up, we have no need to worry about drivers that > are not capable of handling remapped dma address any more. > > Did I miss anything?
I prefer to removing IDENTMAP_GFX in this series and put a comment explaining why Azalia device has no problem.
Then send a separate patch to remove the GFX workaround option. If there is any valid usage still relying on that, it's easy to revert.
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