linux-kernel - Re: [PATCH 1/4] vmalloc: lift the arm flag for coherent mappings to common code

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Message-ID: <20190830092918.GV13294@shell.armlinux.org.uk>
Date:   Fri, 30 Aug 2019 10:29:18 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Christoph Hellwig <hch@....de>
Cc:     iommu@...ts.linux-foundation.org,
        Robin Murphy <robin.murphy@....com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-xtensa@...ux-xtensa.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] vmalloc: lift the arm flag for coherent mappings to
 common code

On Fri, Aug 30, 2019 at 08:29:21AM +0200, Christoph Hellwig wrote:
> The arm architecture had a VM_ARM_DMA_CONSISTENT flag to mark DMA
> coherent remapping for a while.  Lift this flag to common code so
> that we can use it generically.  We also check it in the only place
> VM_USERMAP is directly check so that we can entirely replace that
> flag as well (although I'm not even sure why we'd want to allow
> remapping DMA appings, but I'd rather not change behavior).

Good, because if you did change that behaviour, you'd break almost
every ARM framebuffer and cripple ARM audio drivers.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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