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From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	linuxppc-dev@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>
Subject: Re: generic DMA bypass flag
Date: Sat, 16 Nov 2019 07:22:58 +0100	[thread overview]
Message-ID: <20191116062258.GA8913@lst.de> (raw)
In-Reply-To: <9c8f4d7b-43e0-a336-5d93-88aef8aae716@arm.com>

On Fri, Nov 15, 2019 at 06:12:48PM +0000, Robin Murphy wrote:
> And is that any different from where you would choose to "just" set a 
> generic bypass flag?

Same spots, as intel-iommu moves from the identify to a dma domain when
setting a 32-bit mask.  But that means once a 32-bit mask is set we can't
ever go back to the 64-bit one.  And we had a couple drivers playing
interesting games there.  FYI, this is the current intel-iommu
WIP conversion to the dma bypass flag:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-bypass

  reply	other threads:[~2019-11-16  6:24 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13 13:37 generic DMA bypass flag Christoph Hellwig
2019-11-13 13:37 ` [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device Christoph Hellwig
2019-11-13 13:37 ` [PATCH 2/2] powerpc: use the generic dma_ops_bypass mode Christoph Hellwig
2019-11-13 14:45 ` generic DMA bypass flag Robin Murphy
2019-11-14  7:41   ` Christoph Hellwig
2019-11-15 18:12     ` Robin Murphy
2019-11-16  6:22       ` Christoph Hellwig [this message]
2019-11-19 17:41         ` Robin Murphy
2019-11-20 11:16           ` Christoph Hellwig
2019-11-21  7:34           ` Christoph Hellwig
2019-11-21 16:44             ` Robin Murphy

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