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

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Date: Mon, 29 Jan 2024 15:24:39 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: "Tian, Kevin" <kevin.tian@...el.com>,
 Christoph Hellwig <hch@...radead.org>
Cc: baolu.lu@...ux.intel.com, 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

On 2024/1/29 14:08, Tian, Kevin wrote:
>> 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.
> 

You both are right.

I will add above in the commit message and Cc graphic guys with a new
upgraded version.

Best regards,
baolu