From: Jason Gunthorpe <jgg@nvidia.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>,
Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>,
"Joerg Roedel (AMD)" <joro@8bytes.org>,
linux-arm-msm@vger.kernel.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Prakash Gupta <prakash.gupta@oss.qualcomm.com>
Subject: Re: [PATCH] iommu/io-pgtable-arm: Add support for contiguous hint bit
Date: Wed, 15 Jul 2026 09:50:39 -0300 [thread overview]
Message-ID: <20260715125039.GA50536@nvidia.com> (raw)
In-Reply-To: <2ce09e84-c57f-4087-9dda-07245fadfc02@arm.com>
On Wed, Jul 15, 2026 at 01:14:18PM +0100, Robin Murphy wrote:
> Conversely though, I really wouldn't want to have to maintain arm-smmu
> supporting two completely different pagetable APIs simultaneously either :/
Does arm-smmu era HW even support CONT?
AFAICR the biggest issue with arm-smmu was it using IO_PGTABLE_ARMV7S
as well. I think it would be fine to implement all the unique LPAE
features it needs in iommupt, I did most of them already.
I do have an ARMV7S implementation for iommupt, but I did not solve
the sub page problem. So while it is functionally working it is not
usable since it wastes so much memory. That's a tricky problem to
solve since the algorithms depend on the gather->freelist.
I didn't spend any time trying to do anything about this as I was not
intending to touch arm-smmu
Jason
next prev parent reply other threads:[~2026-07-15 12:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-18 9:02 [PATCH] iommu/io-pgtable-arm: Add support for contiguous hint bit Vijayanand Jitta
2026-06-19 19:40 ` Daniel Mentz
2026-06-25 5:47 ` Vijayanand Jitta
2026-07-03 16:12 ` Jason Gunthorpe
2026-07-07 23:04 ` Daniel Mentz
2026-07-07 23:58 ` Jason Gunthorpe
2026-07-15 5:55 ` Vijayanand Jitta
2026-07-15 11:39 ` Jason Gunthorpe
2026-07-15 12:03 ` Will Deacon
2026-07-15 12:14 ` Robin Murphy
2026-07-15 12:50 ` Jason Gunthorpe [this message]
2026-07-15 12:28 ` Jason Gunthorpe
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