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Date: Wed, 13 Mar 2024 09:46:36 +0200
From: Leon Romanovsky <leon@kernel.org>
To: Christoph Hellwig <hch@lst.de>
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Subject: Re: [RFC RESEND 00/16] Split IOMMU DMA mapping operation to two steps
Message-ID: <20240313074636.GV12921@unreal>
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In-Reply-To: <20240312212844.GA3018@lst.de>

On Tue, Mar 12, 2024 at 10:28:44PM +0100, Christoph Hellwig wrote:
> On Sun, Mar 10, 2024 at 11:35:13AM +0200, Leon Romanovsky wrote:
> > And you will need to have a way to instruct that pin_user_pages() variant
> > to continue anyway, because you asked for FOLL_PCI_P2PDMA. Without that
> > force, you will have !FOLL_PCI_P2PDMA behaviour.
> 
> I don't understand what you mean.

Jason talked about the need to call to pin_user_pages(..., gup_flags | FOLL_PCI_P2PDMA, ...),
but in your proposal this call won't be possible anymore.

> 
> > When you say "simplify the overall interface", which interface do you mean?
> 
> Primarily the dma mapping interface.  Secondarily also everything around
> it.

OK, thanks