From: Jason Gunthorpe <jgg@ziepe.ca>
To: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>
Cc: Daniel Drake <dan@reactivated.net>,
"Joerg Roedel (AMD)" <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Florian Fainelli <florian.fainelli@broadcom.com>,
Broadcom internal kernel review list
<bcm-kernel-feedback-list@broadcom.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 4/6] iommu/generic_pt: Add Broadcom BCM2712 page table format
Date: Mon, 13 Jul 2026 09:00:53 -0300 [thread overview]
Message-ID: <20260713120053.GE1835788@ziepe.ca> (raw)
In-Reply-To: <CAPhyPA5CqCzsDZg1_Sfr=EP5G6uLnnvDmdd_REZPX_VpwS=VJA@mail.gmail.com>
On Mon, Jul 13, 2026 at 11:02:15AM +0100, Nick Hollinghurst wrote:
> Hi Daniel,
>
> On Sun, 12 Jul 2026 at 22:19, Daniel Drake <dan@reactivated.net> wrote:
> >
> > The BCM2712 IOMMU implements a 2-level page table format. It is relatively
> > simple, with one unusual aspect: leaf entries can only be installed at
> > Level 0.
>
> I should admit that a single-level huge page mapping is possible, but
> I was too lazy to implement it (and haven't much tested it).
>
> It can be done by setting bits 31, 30 and 28 of the top-level entry
> (all other combinations of bits 31, 30 will point to a next-level
> table). The page number is in 4K units but must be 4MB aligned.
Let's do that instead of the weird full level contiguation page thing
please
Jason
next prev parent reply other threads:[~2026-07-13 13:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-12 21:18 [PATCH 0/6] Add support for Broadcom BCM2712 IOMMU driver (Raspberry Pi 5) Daniel Drake
2026-07-12 21:18 ` [PATCH 1/6] generic_pt: allow missing sw bit in DMA_INCOHERENT case Daniel Drake
2026-07-12 22:00 ` Jason Gunthorpe
2026-07-12 21:18 ` [PATCH 2/6] iommupt: allow full-table contiguous leaves in unit tests Daniel Drake
2026-07-12 22:02 ` Jason Gunthorpe
2026-07-12 21:18 ` [PATCH 3/6] dt-bindings: iommu: Add Broadcom BCM2712 IOMMU Daniel Drake
2026-07-13 9:16 ` Krzysztof Kozlowski
2026-07-12 21:18 ` [PATCH 4/6] iommu/generic_pt: Add Broadcom BCM2712 page table format Daniel Drake
2026-07-12 22:05 ` Jason Gunthorpe
2026-07-13 10:02 ` Nick Hollinghurst
2026-07-13 12:00 ` Jason Gunthorpe [this message]
2026-07-12 21:18 ` [PATCH 5/6] iommu: Add Broadcom BCM2712 IOMMU driver Daniel Drake
2026-07-12 22:11 ` Jason Gunthorpe
2026-07-12 21:18 ` [PATCH 6/6] arm64: dts: broadcom: bcm2712: Add GPU IOMMU and IOMMU cache nodes Daniel Drake
2026-07-13 9:17 ` Krzysztof Kozlowski
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