On Mon, Mar 16, 2026 at 12:17:39PM -0700, Randy Dunlap wrote: > > > On 3/16/26 12:06 PM, Leon Romanovsky wrote: > > diff --git a/Documentation/core-api/dma-attributes.rst > > b/Documentation/core-api/dma-attributes.rst > > index 48cfe86cc06d7..441bdc9d08318 100644 > > --- a/Documentation/core-api/dma-attributes.rst > > +++ b/Documentation/core-api/dma-attributes.rst > > @@ -163,3 +163,19 @@ data corruption. > > > > All mappings that share a cache line must set this attribute to suppress > > DMA > > debug warnings about overlapping mappings. > > + > > +DMA_ATTR_REQUIRE_COHERENT > > +------------------------- > > + > > +DMA mapping requests with the DMA_ATTR_REQUIRE_COHERENT fail on any > > +system where SWIOTLB or cache management is required. This should only > > +be used to support uAPI designs that require continuous HW DMA > > +coherence with userspace processes, for example RDMA and DRM. At a > > +minimum the memory being mapped must be userspace memory from > > +pin_user_pages() or similar. > > + > > +Drivers should consider using dma_mmap_pages() instead of this > > +interface when building their uAPIs, when possible. > > + > > +It must never be used in an in-kernel driver that only works with > > +kernal memory. > > kernel
Thanks, let's hope that it is the only one comment :). > > -- > ~Randy >
