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Date:   Wed, 30 Jun 2021 08:07:48 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Jason Wang <jasowang@redhat.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        David Woodhouse <dwmw2@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        Alex Williamson <alex.williamson@redhat.com>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        Robin Murphy <robin.murphy@arm.com>,
        David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [RFC] /dev/ioasid uAPI proposal
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On Mon, Jun 07, 2021 at 11:14:24AM -0300, Jason Gunthorpe wrote:
> "non-coherent DMA" is some general euphemism that evokes images of
> embedded platforms that don't have coherent DMA at all and have low
> cost ways to regain coherence. This is not at all what we are talking
> about here at all.

It literally is the same way of working.  And not just low-end embedded
platforms use this, but a lot of older server platforms did as well.