[PATCH v6 7/9] dma-buf: system_heap: Enforce shared-granule alignment for cc-shared buffers

[Jason Gunthorpe]

On Fri, Sep 18, 2026 at 05:39:55PM +0200, Christian König wrote:

> > Arch code can figure out how to do it. If some ARM configs only give
> > order 4 folios or whatever then dmabuf heap doesn't care.
> 
> The fundamental problem is that DMA allocations are highly
> architecture and device specific while Linux memory allocation APIs
> are generic.

This isn't a dma allocation, this is a memory allocation.

We made things so the CC shared folios are DMA mappable through the
DMA API. From the heap perspective the only difference is passing an
additional DMA_ATTR_CC_SHARED when DMA mapping the folio.

Jason