On Mon, Mar 09, 2026 at 05:05:02PM +0200, Leon Romanovsky wrote: > Regarding failure on unsupported systems, I have tried more than once to > make the RDMA fail when the device is known to take the SWIOTLB path > in RDMA and cannot operate correctly, but each attempt was met with a > cold reception: > https://lore.kernel.org/all/d18c454636bf3cfdba9b66b7cc794d713eadc4a5.1719909395.git.l...@kernel.org/
I think alot of that is the APIs used there. It is hard to determine if SWIOTLB is possible or coherent is possible, I've also hit these things in VFIO and gave up. However, DMA_ATTR_REQUIRE_COHERENCE can be done properly and not leak alot of dangerous APIs to drivers (beyond itself). It is also more important now with CC systems, I think. Jason
