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Date:   Thu, 20 Jan 2022 16:28:58 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Keith Busch <kbusch@kernel.org>
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Subject: Re: Phyr Starter
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On Thu, Jan 20, 2022 at 07:27:36AM -0800, Keith Busch wrote:
> It doesn't look like IOMMU page sizes are exported, or even necessarily
> consistently sized on at least one arch (power).

At the DMA API layer dma_get_merge_boundary is the API for it.