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From: Leon Romanovsky <leon@kernel.org>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Marek Szyprowski" <m.szyprowski@samsung.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Petr Tesarik" <ptesarik@suse.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Shuah Khan" <skhan@linuxfoundation.org>,
	"Jason Wang" <jasowang@redhat.com>,
	"Xuan Zhuo" <xuanzhuo@linux.alibaba.com>,
	"Eugenio Pérez" <eperezma@redhat.com>,
	iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, virtualization@lists.linux.dev,
	linux-rdma@vger.kernel.org
Subject: Re: [PATCH 2/3] dma-mapping: Clarify valid conditions for CPU cache line overlap
Date: Tue, 10 Mar 2026 20:27:29 +0200	[thread overview]
Message-ID: <20260310182729.GG12611@unreal> (raw)
In-Reply-To: <20260310123405.GR1687929@ziepe.ca>

On Tue, Mar 10, 2026 at 09:34:05AM -0300, Jason Gunthorpe wrote:
> On Tue, Mar 10, 2026 at 10:45:38AM +0100, Marek Szyprowski wrote:
> > Jason is right. Indeed the rdma/uverbs case needs some extension to 
> > ensure that the coherent mapping is used, what is not possible now. This 
> > however doesn't mean that the DMA_ATTR_CPU_CACHE_OVERLAP is not needed 
> > for that use case too. I'm open to accept both. The only question I have 
> > is which name should we use? We already have DMA_ATTR_CPU_CACHE_CLEAN, 
> > while DMA_ATTR_CPU_CACHE_OVERLAP and 
> > DMA_ATTR_DEBUGGING_IGNORE_CACHELINES were proposed here. The last seems 
> > to be most descriptive.
> 
> If we do DMA_ATTR_REQUIRE_COHERENCE then I imagine it would internally
> also set DMA_ATTR_DEBUGGING_IGNORE_CACHELINES, but I'd prefer that
> detail not leak into the callers.

Yes, this is how I implemented in my v2, which I didn't send yet :).

Thanks

> 
> Jason

  reply	other threads:[~2026-03-10 18:27 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-07 16:49 [PATCH 0/3] RDMA: Enable runs with DMA debug enabled Leon Romanovsky
2026-03-07 16:49 ` [PATCH 1/3] dma-debug: Allow multiple invocations of overlapping entries Leon Romanovsky
2026-03-07 16:49 ` [PATCH 2/3] dma-mapping: Clarify valid conditions for CPU cache line overlap Leon Romanovsky
2026-03-08 18:19   ` Jason Gunthorpe
2026-03-08 18:49     ` Leon Romanovsky
2026-03-08 23:09       ` Jason Gunthorpe
2026-03-09  9:03         ` Leon Romanovsky
2026-03-09 12:30           ` Marek Szyprowski
2026-03-09 13:20             ` Jason Gunthorpe
2026-03-09 15:05             ` Leon Romanovsky
2026-03-09 15:13               ` Jason Gunthorpe
2026-03-10  9:45                 ` Marek Szyprowski
2026-03-10 12:34                   ` Jason Gunthorpe
2026-03-10 18:27                     ` Leon Romanovsky [this message]
2026-03-10 21:08                     ` Marek Szyprowski
2026-03-10 23:34                       ` Jason Gunthorpe
2026-03-07 16:49 ` [PATCH 3/3] RDMA/umem: Tell DMA debug that cacheline overlap is expected Leon Romanovsky

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