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Date: Tue, 23 May 2023 18:06:23 +0200
From: Joerg Roedel <joro@8bytes.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: will@kernel.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jakub Kicinski <kuba@kernel.org>,
	John Garry <john.g.garry@oracle.com>
Subject: Re: [PATCH v4] iommu: Optimise PCI SAC address trick
Message-ID: <ZGzkf68s_0H-jFS7@8bytes.org>
References: <b8502b115b915d2a3fabde367e099e39106686c8.1681392791.git.robin.murphy@arm.com>
 <ZDk83vpIarQ9jWa7@8bytes.org>
 <cef7bb32-a302-2220-68a6-726b45f91769@arm.com>
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In-Reply-To: <cef7bb32-a302-2220-68a6-726b45f91769@arm.com>

On Fri, Apr 14, 2023 at 06:45:57PM +0100, Robin Murphy wrote:
> Sounds good - I'm considerably more confident in this approach, but although
> it should not be able to break any scenario which wasn't already broken, it
> could potentially still make such a breakage more noticeable. Thus in all
> honesty I'd feel happiest giving it a full cycle of -next coverage as well.

I had some second thoughts on this, wouldn't it be better to change the
allocator to allocate from lowest addresses first? Then we can just
remove the SAC trick and rely on dma-masks only.

Thoughts?

Regards,

	Joerg