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Date: Tue, 9 Jul 2024 08:20:15 +0200
From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Christoph Hellwig <hch@lst.de>, Leon Romanovsky <leon@kernel.org>,
	Jens Axboe <axboe@kernel.dk>, Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Keith Busch <kbusch@kernel.org>, "Zeng, Oak" <oak.zeng@intel.com>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Sagi Grimberg <sagi@grimberg.me>,
	Bjorn Helgaas <bhelgaas@google.com>,
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	Kevin Tian <kevin.tian@intel.com>,
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	=?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
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	linux-rdma@vger.kernel.org, iommu@lists.linux.dev,
	linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org,
	kvm@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH v1 00/18] Provide a new two step DMA API mapping API
Message-ID: <20240709062015.GB16180@lst.de>
References: <cover.1719909395.git.leon@kernel.org> <20240705063910.GA12337@lst.de> <20240708235721.GF14050@ziepe.ca>
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On Mon, Jul 08, 2024 at 08:57:21PM -0300, Jason Gunthorpe wrote:
> I understand the block stack already does this using P2P and !P2P, but
> that isn't quite enough here as we want to split principally based on
> IOMMU or !IOMMU.

Except for the powerpc bypass IOMMU or not is a global decision,
and the bypass is per I/O.  So I'm not sure what else you want there?