linux-kernel - RE: [PATCH 1/1] iommu/vt-d: Remove INTEL_IOMMU_BROKEN_GFX

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Date: Mon, 29 Jan 2024 06:08:33 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Christoph Hellwig <hch@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>
CC: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>, "Robin
 Murphy" <robin.murphy@....com>, Jason Gunthorpe <jgg@...pe.ca>,
	"iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/1] iommu/vt-d: Remove INTEL_IOMMU_BROKEN_GFX_WA

> From: Christoph Hellwig <hch@...radead.org>
> Sent: Monday, January 29, 2024 2:03 PM
> 
> On Sat, Jan 27, 2024 at 02:45:12PM +0800, Lu Baolu wrote:
> > Commit 62edf5dc4a524 ("intel-iommu: Restore DMAR_BROKEN_GFX_WA
> option for
> > broken graphics drivers") was introduced 24 years ago as a temporary
> > workaround for graphics drivers that used physical addresses for DMA and
> > avoided DMA APIs. This workaround was disabled by default.
> >
> > As 24 years have passed, it is expected that graphics driver developers
> > have migrated their drivers to use kernel DMA APIs. Therefore, this
> > workaround is no longer required and could been removed.
> 
> How about you Cc the intel graphics maintainers and get a confirmation?
> 

in the worst case there is still "igfx_off" option available to achieve the
same effect.

there is really no good reason to keep this config option so long while it
was intended to be removed in 2.6.32.

but yes the Intel graphics maintainers should be CCed.