Re: [PATCH 2/3] dma-mapping: Clarify valid conditions for CPU cache line overlap

[Leon Romanovsky]

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