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Date: Tue, 31 Mar 2026 22:02:20 +0300
From: Leon Romanovsky <leon@kernel.org>
To: Keith Busch <kbusch@kernel.org>
Cc: Zhiping Zhang <zhipingz@meta.com>, Jason Gunthorpe <jgg@ziepe.ca>,
	Bjorn Helgaas <bhelgaas@google.com>, linux-rdma@vger.kernel.org,
	linux-pci@vger.kernel.org, netdev@vger.kernel.org,
	dri-devel@lists.freedesktop.org, Yochai Cohen <yochai@nvidia.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	Bjorn Helgaas <helgaas@kernel.org>
Subject: Re: [RFC v2 1/2] vfio: add callback to get tph info for dmabuf
Message-ID: <20260331190220.GI814676@unreal>
References: <20260324234615.3731237-1-zhipingz@meta.com>
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 <20260325082534.GN814676@unreal>
 <acW2BwQKaUbS3eL9@kbusch-mbp>
 <20260331083758.GA814676@unreal>
 <acvFV8c5QVxnt3Em@kbusch-mbp>
 <20260331132942.GC814676@unreal>
 <acvNsvS5ShlQlrox@kbusch-mbp>
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In-Reply-To: <acvWplw67b3Gwlkc@kbusch-mbp>

On Tue, Mar 31, 2026 at 08:13:58AM -0600, Keith Busch wrote:
> On Tue, Mar 31, 2026 at 05:03:09PM +0300, Leon Romanovsky wrote:
> > I understand, my proposal is always set TPH flag when new struct is
> > used.
> 
> An existing application recompiled against the new kernel api implicitly
> uses the new struct layout without setting the TPH flag, so kernel and
> application are out of sync on where dma_ranges exists with your
> proposal.

Right, what about adding TPH fields to struct vfio_region_dma_range
instead of struct vfio_device_feature_dma_buf?

Thanks